Saturday, 26 September 2015

Thinking About Leaves, more on Vellum

This week I've been continuing with the 30 day challenge and came back to the old problem with painting leaves....nothing lets a botanical painting down more than poorly painted foliage and the worst case scenario is badly painted leaf on vellum! Don't think no one will notice if your leaves aren't up to scratch....they will! It's always worth brushing up on leaves so this week I've been preparing new tasks for some of my students and leaves are always firmly on the agenda for me too. ...they need constant practice.

Here's a video of a leaf I painted on vellum this morning, sped up x16 so that gives you an idea of the actual time frame.




Almost finished, the autumn leaf on vellum
I love to paint leaves and autumn is the most exciting time with a variety of rich colours. Tidy edges are vital, as are clean highlights which should not lifted, overworking is an absolute no-no! it's always obvious if you do any of these, so there is no hiding place with leaves. Best advice is to keep it clean.... if it's not.... well forget it and start over until its right!

Rough measurements of a leaf in perspective

I believe that it really is all about observation of the the light and shade, so often I see leaves painted in a 'stylised' fashion, with 'tramline veins' that don't mirror the actual venation of the leaf. My recommendation is always to 'really look' at leaf and forget what you think know and just 'see' what's really there. Yes always take basic measurements of height, width and widest point etc. get the facts first but then look at how the light hits the subject. Start with a leaf portrait first and then move on to leaves perspective. Here are some of my leaf portraits from over the years.
Cherry leaf on vellum from around 2007. The thing I really love about vellum is the way its possible to 'polish' the surface and creates a shine. Work on vellum should never have thickened paint at the edges and should take full advantage of the translucency that can be achieved on this surface but you can also create that lovely texture using the different dry brush techniques

Decaying lime leaf on vellum, again vellum is great for detail and translucency, A sharp pointed brush is required, such as W & N series 7 miniature, size 4 and 1

Hydrangea on Fabriano artistico..... the technique is much the same as for vellum, lots of dry brush work over the wash.

Herb Robert on Fabriano artistico, love the rich autumn colours. Transparent colours are a must. I like Transparent Yellow and Nickel Azo Yellow in leaf mixes is a favourite. Steer clear of opaque yellows and try to have no more than 3 single pigment colours if you want to keep it fresh looking.

One of my early leaves on vellum. Horse Chestnut on Kelmscott, maybe 2008

Cherry with a leaf minor cast, 2010




Lime leaf on vellum, 2010

Mahonia on vellum, with some lovely dacay!

Red Maple on vellum


Red Maple on paper

Shiny dark greens with the Camellia on paper. Cerulean or Manganese blue makes a good 'shine' colour on those dark green leaves

Building up the layers on vellum.....doesn't always look so neat in the early stages. I use a 5 stage process which I've developed and I believe it works.

.........you can get a great shine in the end!
This one on natural vellum is perfect for decaying leaves but a little less suitable for flowers

My process is pretty much the same on paper but less washes are possible on vellum, this is  a rhododendron leaf on paper.Stippling dry brush over a wash similar to vellum


Leaf portraits are fun to do and you can learn much from them! They always sell well too, so why not start a leaf library.





Saturday, 12 September 2015

30 Paintings on Vellum in 30 Days

Haven't written a blog post for over almost a month and it's really bothering me! There's one in the offing about photographing artwork but it requires some use of the grey matter to finish it off, so here's s something about the new 30 Day Challenge in the meantime. It was initiated on the Botanical Artist's Facebook Group, and requires 30 small works to be completed during September. Over the past few years I've tried a few of these Challenges, here's a link to one that I actually completed in 2013, and wrote a daily blog for.
This time I wanted to try something different so have decided to do all 30 on vellum....it is do-able if I keep it simple!

Day 5-10 Violas on Kelmscott Vellum, size approx 8 x 6. I bought these little pots of flowers from the local DIY store and painted the whole sheet in one day because I was so behind. The palette included: Holbein Manganese Blue PB33 ( not the hue) with W & N Cobalt Violet and Quin Magenta. I love the way PB33 separates, it's really useful for high light value pale violet flowers, with both pink and blue  present. Also Violet Dioxazine. Lemon Yellow NT and Cadmium Yellow for the flower centres. The greens included Cobalt Violet, Lemon Yellow and permanent rose. 

 The Challenge started while I was away in Italy, where I visited the Venice Biennale, it's good to view a diverse range of art and the Biennale was certainly that! diversity definitely feeds the brain and upon my return I was was left playing 'catch-up' with the Challenge but definitely inspired to work.

I try to tie in this sort of challenge with other work, and these little studies are prefect for video examples for my new online Vellum Course which is underway with 5 great new students. Currently I'm also working on a large vellum painting of Roses on vellum so no doubt a few roses will probably feature here and there. Here's a little bud of Olivia Rose Austin, which was my 4th painting.

pink rose bud on vellum
No 4. Olivia Rose Austin Bud. 5 x 3 inches on Kelmscott. Colours: Permanent Rose and Lemon Yellow n.t. for the pink with Cobalt Violet for the cool pink shades. A small amount of Permanent Carmine was also used to deepen the colour . The green mix is Cobalt Blue, Transparent Yellow and Permanent Rose. The stem Perm rose, Trans Yellow and Brown Madder
 The Blackberry studies are good as preparatory works for another painting, which is for a  competition, the final piece will be on a piece of mounted natural vellum though. This is more challenging than the Kelmscott but this piece is all good practice with the subject.

Blackberries watercolour painted on kelmscot vellum
Day 1. Blackberry Study on Kelmscott, approx 7 x 5.5 inches. Love painting blackberries and working with dark colours. The black mix is Indanthrene Blue, Permanent Carmine and a very small amount of Trans Yellow. The bias of the mix is on the violet side. Where the fruit is more of a dark red colour, the quantity of Permanent  Carmine is increased. The red is Perm Carmine and Scarlet lake for the warmer red. Stems and all other parts are mixed from the same 4 colours. There is really mo need for lots of colours when a few will do and the use of the same colours created better harmony in a painting.

Blackberry leaf and fruit painted on vellum with black paint
No. 3 This is a simple study of a single fruit and leaf but painted with Ivory Black. This is a very thick piece of vellum 6 x 2 inches. I quite like this effect and have been playing with it recently. It's all about getting the tone right before working with colour. It's also an approach that I teach as good practice in preparatory work.
Also completed on the first day was a simple single maple seed, not particularly well painted but very quickly completed.  I used the earth colours for this, it was a pretty lazy effort. In the 2013 Challenge a maple seed was the first subject and it seemed a good idea to repeat on vellum.

Maple seed painted in watercolour on vellum
Maple seed on Kelmscott, 3 x 2.7  inches. I used some Manganese Blue on the shine. Thereafter Raw Umber wash, followed by building texture with Brown Madder and Van Dyke Brown, a small amount of Ultramarine Violet was added for the shadows. Lots of sweeping and drawing dry brush work here.
I've almost caught up! Maybe I'll even manage all 30. Ive plenty of vellum off - cuts so no excuses.

The Photographing artwork post will hopefully follow shortly.

Saturday, 11 July 2015

Everything's Coming up Roses! The First Studies

A few weeks ago I visited the David Austin Garden, which is less than an hours drive from my home.  In the past I haven't been a huge fan of roses and only ever illustrated a few in all the years I've been painting.... but decided it was time to give the roses another chance. The garden is probably one of the best I've ever seen and got me completely hooked on roses. I purchased three plants and the painting commenced! Roses seem to be one of the more challenging subjects in the world of botanical painting, so I'm open minded about the success of this project. Will split this into two separate posts, this one is about my preparatory studies for Olivia Rose Austin and Munstead Wood.

Olivia rose austin botanical study in watercolour
First study page of Olivia Rose Austin
I had intended to buy an old rose but got drawn in by 'Olivia Rose Austin', which is an English Leander hybrid and has only been available since 2014. With its large pale pink cupped blooms, this rose is named after David Austin's granddaughter, so I guess they must think it's pretty special too! It blooms three times a year instead of the usual two, so I'm hoping that buys me some time. This rose along with a couple more,  Munstead Wood and Sceptre d' Isle, should keep me busy for a while. 

Pink roses photograph in the David Austin Garden, UK
Olivia Rose Austin in full bloom in late June at the David Austin Garden in Albrighton

I couldn't write a post without a few photographs of the David Austin Garden, so here it is.....a feast of roses!
Renaissance Garden at the David Austin Rose Garden, UK
The Renaissance Garden

Rose archway at the David Austin Garden
Beautiful archways and climbers can be seen throughout the garden. There are several different areas, including a Victorian walled garden, here the doorway looks in from the Long garden to the Lion Garden. 

I took well over 500 photographs and several videos on my iPhone. I returned again the following week for another look and although it was just one week later it's wasn't quite as spectacular. There is also a species garden and it was interesting to note how many bees were found in this area. Here's a short clip of typical of a very busy little bee. If the current paintings go well ( fingers crossed!) I'd like to paint some of the Scottish species roses next year.

Where to start: the study page approach for Olivia Rose Austin
I plan to paint the final works on kelmscott vellum and have a whole skin waiting on top of the wardrobe. But my initial approach is to complete sketchbook and then a number of study pages, the study page is the focus of this post. These studies are painted on A2 Fabriano Artistico watercolour paper ( I40lb HP) but a study page should be painted to suit the size and structure of a plant. 
drawing board with roses
I don't plan a layout for a study page but place the elements randomly with fairly even spacing on the sheet.
Because the final piece will be on vellum a number of small colour studies on off-cuts of vellum will be completed too, I do this because the colour will be different on vellum compared to paper. This study page approach allows me to get to grips with the subject and stimulates ideas for a composition. It's not painted in great detail and probably takes 2 or 3 days to complete. But I don't set a limit...it takes however long it takes.  Most importantly though it enables me to get to know the subject and to understand the character of a plant, such as the growth habit, and in this case the changing morphological features and colours of the blooms.
Painting study pages is particularly important to me especially for a plant that I'm less familiar with. It's similar how a portrait artist needs to capture the character of a sitter, so the botanical artist must capture the particular character of a plant. I use this approach with all of my own work and all of my students are 'forced' to do it too. Those student who really commit to study page work, instead of skipping over it,  seem to get the best results in the long term.
rose detail Olivia
Detail from page 1 of the study: Different stages of flowering, with faded older blooms, spent flower and bud.
Rose sketch on vellum
Colour test on vellum. I paint these directly to vellum 6 x 4 inch off-cuts without drawing, they take about 30 mins to complete. I paint the flower rather than just swatches of colour because the layering of colour needs to be understood in an actual subject. I make notes on the sheet and keep for reference, noted include the colours and descriptive information, such as the fact that the opening bud is a stronger pink than the open flower. Fortunately not much adjustment in colour was needed for vellum, slightly less yellow was required because of the base colour of the surface. 
 In a study page the aim is to collect as much information as possible, written descriptive notes and illustrations of the plant parts that may be useful, such as different aspects of the flower, buds, leaves etc. sometimes I make several pages of studies, basically I continue until I'm happy that I've enough information - there isn't a set formula, it's just common sense. This enables me to work through many of the problem areas before committing to the final painting and reduces the number of potential errors. It's an approach that's probably not suited to everybody - I think mabye having a scientific background reinforces my own methodical approach to planning a painting. Having said that I don't always do a study page and sometimes I complete spontaneous paintings but with new subjects for major works, it's a wise move. 

 How to tackle a complex form
A rose of this type has a complex structure of many petals, after making some initial sketches I developed a reasonable understanding of the petal arrangement. I decided after putting in a feint outline in, that it was easier to sketch directly with watercolour. Then working from the outside to the center seemed to work ok, but keeping careful track. The lack of pencil helped me to keep it very clean and avoided any erasing. I only ever draw in very feint outlines use an eraser as little as possible - even light use can damage the paper surface. The washes need to be very light and carefully layered in a pale flower and detail is added with dry brush.

rose watercolour work in progress
Beginnings. A few pencil guide marks and then paint lightly. I used W & N Permanent Rose mixed with Lemon Yellow nickel titanate to give a soft pink. The yellow is opaque but this works to the advantage with a soft pink giving a creamy soft pink. There is a lot of discussion about not using opaques amongst botanical artists and while I agree that most useful colours are transparent, the opaques also have important place in the paintbox, their value is dependent on the order of washes and the light value of the subject ( but that's another post). I wanted to capture the softness of a rose and so this seemed like a good option. I also added Permanent Magenta for cooler pink and used M.Graham Cobalt Violet for the shade. (note: that despite being the same pigment, the M. Graham CV is much cooler than the W & N version).

rose detail in watercolour
Gradually work into the centre building up the colour
A confusing aspect of rose paintings is the change in the flower, they expand from a fairly simple bud and end up with a mass of petals. The colour changes quite dramatically too, so I painted the rose at different stages of maturity.  
The leaves are quite a challenge with roses and of course any study needs a number of leaf studies. I have a few simple ones on this sheet but will complete more before proceeding with the painting. 
Rose leaf study in watercolour
A simple study of a leaflet. The leaves are all important to any painting, so many paintings are ruined by poor leaves. Roses are pinnately compound leaves, here just the terminal leaflet is shown.  I think rose leaves are possibly one of the most difficult to get right. There is generally lots of fore-shortening involved too, with fine veins and some puckering in the older leaves! I always tackle the leaves first on the painting because to me if the leaves aren't good enough the painting is ruined. For these I used a mix of Indanthrene Blue, Transparent Yellow and Permanent Rose. For greens I pretty much always try to use transparent colours. I keep the mix to 3 or less colours of single pigment and generally use a small amount of 'red'  to make the green more natural colour. If the red is one I used in the flower I use the same in the green mix.
I also did some research on other paintings of roses, from the obvious Redoute paintings to some contemporary painters. One of my favourite paintings of a rose is Martin Allen's beautiful single pink rose, also Kate Nessler's roses on vellum are old favourites of mine.


Munstead Wood 
I wanted to capture all of the roses and they were all flowering together, so decided to complete the study pages for all first. Munstead wood is an English old rose hybrid and very different rose from Olivia with its rich dark wine and magenta coloured blooms. It's another beautiful fragrant rose and reminds me of childhood days spent collecting rose petals from my grandmothers garden.  
Munstead wood rose watercolour painting
Munstead wood study page underway. A very dark flower which changes colour from a crimson bud to a deep magenta or burgundy flower.
Colour testing for Mustead Wood rose
A difficult coloured flower, that changes colour over time. I used a combination of Permanent Magenta, Permanent carmine, Violet Dioxazine. Also for the bright glazes Quin Magenta and Quin Rose. An a little neutral tint for the deep shade.
Munstead wood flower in watercolour
The open bloom has many petals and appears two-tone in colour as it changes.
I've a little more work to do on the study pages and will then move on to the composition, so will continue with this post at a later date to describe the process of composition. Thereafter the final painting on vellum will begin. Hopefully I can complete it this year while the roses are still flowering. If not I prefer to wait until the following year when the plants flower again. I could continue from photographs but only do this if I absolutely have to. 

One thing I have noticed is that painting roses is a messy business! All of a sudden the petals drop on mass! they fall into the water and on to the palette, resulting in this rather nice effect!

paint palette wit impression of rose petal
Petals in the paint, leave beautiful patterns


Tuesday, 23 June 2015

About Watercolour Paint

I've been resisting writing a post on watercolour paint for a long time. It's a big topic and probably one of the most discussed with beginners and experienced painters alike.... I really did try to keep it brief but failed miserably.....Apologies for this is an epic!  
Photograph of watercolour paints and colour charts
Don't let this happen to you! in my art cupboard, W & N, Schmincke Horadam, Sennelier, M Graham, Daniel Smith, Old Holland, Holbein plus a few other odds and ends have accumulated over the years. But is one brand really better than another?
Despite having a large stash of paints I tend to use relatively few. As an example I list the paints names and pigments I most commonly used for pink and blue flowers (below) but I also like to play with different paints and see no harm in experimenting with other colours. My basic palette comprises all single pigment paints because I figure that you shouldn't really use more than 3 pigments in a mix if you can help it, the more you use the muddier it tends to get. Convenience mixes are made from multiple pigments and could probably mixed from the core palette anyway, also I find I'm clearer with predicting an outcome with the single pigments. Is one brand better than another? probably not because they all have some great and some not so great paints, so I tend to pick and mix brands, using mostly W&N, M.Graham and Daniel Smith with the odd Schmincke. The paints I don't particularly like are Sennelier, I find many of the colours have chalky finish when dry and are disappointing but some of their yellows are quite good. Like other art materials paint choice is also very personal so it's probably inevitable that you will end up with an unused section of the box. 
Pink paint palette with images of paintings
Pinks: all of these flowers were painted with a relatively small selection of different reds or pinks, In the paintbox I use mostly Permanent Rose PV19, Permanent Magenta PV19,  Permanent Alizarin Crimson PR206 and Quin Red PR209, Quin Magenta PR122 and W & N Scarlet Lake PR188 or Pyroll Red PR 255 for most for red/ pink mixes. 
Blue and violet paint palette with imakes of painted flowers
Blue to violet palette: French Ultramarine PB29, Cobalt Blue PB28, Cerulean blue PB35, Pthalo Blue PB15, Indanthrene blue PB 60,  Ultramarine violet PV15 and Cobalt violet PV 14 are the core paints used in my box

I don't profess to be an expert on pigments, I don't even try to remember them but have a vague knowledge of the main ones I use and look them up as needed. It is important to understand a few basics regarding paint properties and to keep the number of paints to a manageable quantity, particularly when learning. I used a fairly limited palette of W & N artist quality paints for well over 20 years before adding any extras and they are one of the better brands and consistent. I don't think having more paints made my painting any better. Sometimes the fancy names and marketing by companies like Daniel Smith and Sennelier make paints seem very attractive and you can end up with far too many, more often than not the 'convenience' mixes are completely unnecessary but they can be fun to play with. I learned from mistakes, by experimenting and reading. If you want to find out about paints I recommend Hilary Page's Guide to Watercolour paints, which is probably one of the most comprehensive tests of different brands, she updates online too. And the excellent Handprint website provides everything you could ever need to know!

I'm afraid I don't paint beautiful elaborate colour charts, painting pages of squares with no particular purpose seems quite pointless to me as the number of variations is infinite but again when learning it can be useful to experiment with colour mixes in this way. Instead I tend to paint colour charts on a 'needs' basis when working on a subject.
How I mix colours 
I'm not saying this is right or wrong - it's just my way.  To match a primary, such as this blue flower below, first of all I refer to a painted chart of all the paints I have of the same hue, I hold the subject next to the samples in good daylight to identify the nearest match. I try to match to the nearest basic hue first. From there I look for the cool and warm variations in relation to light and make a colour chart. After the hue has been identified I consider the saturation of the colour and the tonal values. It's very important to understand these 3 key points. It's surprising how often saturation is confused with tone. I won't go into it here or this post will never end. I think it was covered it in a previous post.
Colour chart for a blue Phacelia flower, showing different blues
Start with the basic hue. I look at all of my blues to see  what's the nearest match to the basic hue. For this Phacelia flower a good starting point  is the M. Graham Ultramarine Blue PB29. It's a red biased blue so  I start with that and then see what I need to add. Then consider the saturation and tonal values. After that I make a colour chart.  


Sketchbook drawing of Phacelia campanularia and the basic blue hues
Starting to work out the basic hues for all the plant parts in the sketchbook. Final colour testing should be done on the same paper as the final painting as each colour looks different on different papers surfaces. After this stage I make a  quick colour study painting, considering the colour on the actual subject in relation the the cool and warm effects
Of course its slightly more difficult when mixing secondary colours as no such direct comparison can be made. I use  primaries to produce greens, which can be the most troublsome colour for beginners. I try to use mostly using transparent or semi transparent paints. I start with the yellow and add the blue. I generally try to work with a blue that has a similar light value to the green that I'm trying to mix. For example a very light grey green will require a high light value blue, such as cerulean PB35. Whereas a dark leaf, such as holly, will require a dark saturated blue, such as Indanthrene PB60 or  Prussian blue PB27.  Often a small amount of red is needed to make a more natural green. I also use overlaid washes to alter a colour, there are several different approaches to achieve a final desired effect. I usually avoid cadmium yellows as I find they are too dense and opaque for good greens.
Sketchbook immage showing green mixes
Greens can prove one of the most difficult mixes for beginners so I recommend making a ssketchbook of greens but working on actual subjects rather than painting endless colour charts that don't relate to actual subjects. This puts green mixes into context.
Orange is another secondary that can be difficult to keep bright and clean, again I favour mixing transparent or semi transparent single pigments, of red such as Daniel Smiths Pyroll Scarlet PO 73 ( also M. Graham Scarlet Pyroll PO 73 which is much more orange) with  yellow, such as W & N Transparent Yellow PY97 or NM. Graham Nickel Azo Yellow PY 150, which makes a fantastic colour.  Quin Coral PR 209 also makes a good light orange. This red / yellow mix allows you to vary the colour bias in relation to light and the orange can easily be adjusted to a red or  yellow bias.  In a subject variations of the orange colour are present, as seen in this painting of a Fritillaria imperialis, where you can see that the shift from cooler yellow/orange on the side where the light source is to warmer red/ orange on the most saturated areas and shade side.

Orange can be a tricky secondary colour mixed using yellow and red pigments, although Daniel Smiths Transparent Pyroll Orange is a nice single pigment orange too for glazes

Orange mixing colour chart
My not very tidy colour charts for the Fritillaria imperialis painting


 I do try make it my business to try to make informed choices when it comes to choosing and using watercolour paints but it's not always easy, in the process accumulated too many paints that will probably outlive me!
This next section is about the basic properties. Followed by a comparison of brands on an actual subject.



Some of the things nobody ever told me....a beginners guide
I can recall having no idea what anybody was talking about when it came to paint properties and feeling a bit foolish, but how was I to know if nobody ever taught me! When I started to learn I realised that I has already discovered many of the the attributes of paints through using them on a regular basis but just didn't know the terminology. 
I purchased my first watercolour box, 36 years ago when I was 15. It had 12 pans of fairly standard colours, you can still buy a similar box today from W & N although the cadmiums are no longer included. The only thing I knew was that my art teacher had told me to buy the artist quality paints.  I wasn't taught anything about paint properties at school or art school or on any . There was no Internet, so I went to my local art store, which is still in business today and purchased the only box of paints in stock using some money I'd saved from my birthday. Here are a few of the basic points that might be useful.


Paint properties
Each tube or pan of paint in your paintbox has a different properties listed, pigments, lightfast or  ASTM ratings, transparency or opacity, staining properties etc. are all listed on the tube or on a colour chart.
A tube of M. Graham cobalt violet with paint properties description
Tube of paint showing properties.
 Thirty five years ago, I just used my paints.....a lot..... and it's the best way to learn. I was pretty happy with them but became slightly frustrated by a 'flatness' that was evident in some mixes and couldn't quite achieve the vibrant colours found in nature when I layered washes.I wanted to know more. I started to buy odd few bright colours and moved up a size with the paint box to the 24 pans, which I used for around 20 years before moving on to the wooden box of pans that I still use today. Then I started to add but many colours I hardly ever use. Most important to me was transparency, all watercolours are transparent to some degree but some are more transparent than others.  I also noticed the effect of granulation in certain colours. I also realised that some colours can fade or stain and that they can be made of single or multiple pigments. I started to read and learn more.
 The easiest way to find out about paint properties is to download or send off for a colour chart, many are free from companies such as Jacksons Art.
There are some links at the end of this blog post to download charts. Download the chart and simply paint your own version and write on the properties and observational notes. Keep it in your paintbox or on your drawing board for reference ( One of mine is shown in the  image below).
Keep a painted chart in the lid of your paintbox and another on your drawing board, which shows the full strength and in glazes.
 Types of pigment 
Watercolour paints are made of pigment and an aqueous medium which suspends that pigment, with binder, such as gum Arabic (which can crack if there is too much) and a plasticizer, such as honey.

As a simple explanation, there are broadly two types of pigments  
1. Inorganic or mineral,  which are derived from the earth's minerals and include many opaque colours, these include the natural earth colours such as the ochres and siennas or the synthetic mostly metallic elements such as the cobalts and cadmiums
2. Organic pigments which are created in a laboratory, are derived from either natural animal or plant matter or from synthetic oil based chemicals include many of the bright transparent colours, such as the quinocridones pthalo, dioxazine and hansa colours.  They are very useful to the botanical artist because they allow us to create the bright colours found in nature.
 
Image of ultramarine paint pigment
Natural Ultramarine Pigment derived from the mineral Lapis Lazuli copyright Wikimedia Commons

Before the Industrial revolution and the development of synthetic pigments the artist had a much more limited palette. Pigments were hard to extract an prices of certain pigments were prohibitive. Today, with synthetic pigments we have a huge range of paints at our disposal. Manufacturers apply all sorts of exotic names to their colours, which tends to attract our attention.

If you look at colour charts or paint tubes or pans you will see that each paint has a brand name, this can be quite misleading and often the name doesn't relate to the pigment. Paints can have the same name but different pigments e.g. Daniel Smith Indian Yellow is  PY 108 and W & N is PY 153. So if you try to but the same colour name in a different brand check the pigment number first. You will also find an an alpha numeric code that starts with P ( Pigment ) then a letter for the pigment followed by a number, e.g. PV 14 and PV 49 are both Cobalt Violet but PV14 is Cobalt Phosphate and PV 49 is a newer pigment which also contains ammonium. Cobalt violet is a favourite of mine I use it a lot for reflected light and seem to have it from several manufacturers! Using single pigments paints is probably the most reliable route for reasons I've already mentioned but even with the same pigment brands do differ considerably as shown below.
three different brands of cobalt violet
Left to right: Daniel Smith PV49, M. Graham PV14 and W & N PV14. A  noticeable difference between each paint. The Daniel Smith is the PV49 and as yet is unrated for lighfastness,  although Hilary page give it an excellent rating,  it seems to have a lot of Gum Arabic and lifts easily, it absorbs the water making it more difficult to handle as it pushes around the paper but  it's a nice colour.  The M Graham has a lovely consistency but doesn't have the pinkness I'd expect in a cobalt violet, but it's good all the same. The W & N has good colour and consistency and an AA lightfast rating. 

Student versus Artist Quality
Artist quality paints are generally superior to student quality because they have higher pigment to mixer ratios, and therefore the tinting quality is superior. The pigment may also be less finely ground or poorer quality with more fillers. If you compare the two you will see that the student quality have a slightly chalky and less translucent appearance. It's worth buying less paints of a better quality.

Pans or Tubes
As a rule of thumb pans are suited to smaller works, painted used a 'dryer' style, whereas tubes which are already suspended in liquid are meant to be used wet. Some tubes, such as M. Graham are suitable for re-wetting.
As a rule of thumb if you like painting wet-in wet and big washes, use tubes but if you prefer fine detail on a smaller scale pans are better. I use a mix of both although I used pans for many years and still prefer them for painting on vellum. I wouldn't recommend buying the full pans unless you are certain it's a s colour you will use a lot.
Pans have a higher pigment ratio and are easy to store and transport, The downside is that they get dirty and fluffy if you forget to close the paintbox lid!  Tubes are good for getting larger amounts of colour onto the palette and a higher paint load on the brush which is advantage when working on larger washes. Don't allow them to dry and reuse unless they are suited to such treatment, some brand degrade when dried. My frustration with tubes is the lids, which never seem to want to go on or weld on so tight that it's almost impossible to get them off. Again neither tubes or pans are better they are just different and you can probably find a use for both.

Lightfastness
The ASTM  ( American Society  for Testing and Materials) is the recognised testing system to assess the lightfasness in paint over time under the effect of light. This system became more stringent in 1983 and as a result manufacturers appear more conscientious regarding the longevity and stability of paints. Paints are rated  I (excellent)  or II ( very good) are tested and known to be reliable. Some florilegiums and societies ask that artists use only paints with these ratings, and if you are selling your work you have a responsibility as an artist to ensure that the work is a permanent as possible. The paints rated III  ( moderate) and IV (poor) should therefore be avoided. A  designation of N/A means the paint has not been rated.  There are several that should be avoided, such as the fugitive Opera, and rose madder genuine, Alizarin Crimson. There are also ratings for fluctuating colour, reaction to acidity / alkalinity and damp. Aureolin is known to which becomes dirty in thin washes.Check the ratings on the colour chart.  You can carry out your own lightfast tests too.

The Watercolour purist method and white paint
This is the method that I use, it basically means that the white of the paper is used instead of adding any white paint, it relies on the transparency of the paints so the paints used need to be carefully considered to ensure that luminosity is retained.  An occasion some white body colour, such as titanium or Chinese white  may be added, such as on the white hairs of a flower or leaf or bloom on a fruit. This is applied last of all and applied fairly dry with a small fine brush. Other than this use white should be avoided.

Painting using body colour to add fine hair to Pulsatilla flower
Watercolours are painted using the purist method, however on occasion and opaque white is added where light coloured hairs are present, as is the case in this Pulsatilla, this is known as 'bodycolour'. Although it appears white it is usually mixed with another colour as pure white can look too harsh or blue. Titanium white is the most opaque of the whites.
Paints with Black
Another reason for single pigment paints is the deadening effect of paints with black. Indigo being a case in point. It may look like a beautiful dark rich blue but when used in a green mix it can kill it stone dead. An example is Daniel Smiths Indigo which is  PB60 and PBk6 - its a mix of Indanthrone blue and black.

 
Transparency and opacity
Transparency is particularly important, so something you really should always check, transparency varies between brands too, e.g. PR 179 Daniel Smith Perylene Maroon is semi transparent and
Winsor & Newton is transparent. As I've already mentioned all watercolours are transparent but some more so than others, so glazing with the transparent gives cleaner result than glazing with opaques or semi-opaques. Sounds obvious but you be surprised how many people are puzzled by the the lack of transparency in there painting yet haven't considered the transparency properties. Generally speaking you need a mix of opaque and transparent in your paint box, although like many botanical artists I prefer more transparent paints, the opaques have their place too and can be good for the first washes to lay a foundations. Thereafter the transparent colours are good for subsequent glazing and allow the light to pass through and preserve the luminosity. Try painting a strips of opaque colour then overlay a transparent colour, and vice versa to see the  difference.


Granulating colours
Some pigments separate from the water and result in a granulated effect, many occur in the blues,, such as French Ultramarine and Cerulean. This can be a desirable feature but may also be an effect that you don't want. The degree of granulation seems to differ between manufacturers  

Staining Pigments
Once you put them on the paper they're there to stay and hard to lift. Examples include the cadmium reds and yellows.

Paints with Hue in their name
Paints with Hue in the name tend to be an imitation of another pigment. For example Manganese Blue Hue. Manganese Blue is no longer available so the Hue is a combination of Pigments to match the original pigment. Many of the Hue paints replace toxic pigments.   

Is one brand preferable to another? A simple test painting the same subject
I don't think so, although some seem to be more consistent. I tried painting the same small subject using the same pigments ( or as near as possible). I used  Daniel Smith, Schmincke, W & N and M. Graham. I decided not to bother with Sennelier as I couldn't match the pigments and don't care for them anyway.

Comparing paint brands on the same subject, red maple seed
Red Maple seeds completed using the same pigments but different brands, top: Daniel Smith and Schmincke ( pans), bottom:  Winsor & Newton (pans) and M. Graham
Maple seeds painted with different brands of paint
I have to say there wasn't much between them but  Winsor & Newton came out slightly ahead of the others, I found I could achieve a much finer finish with them and better transparency. closely followed by M. Graham and Daniel Smith . My least favourite was the Schmincke, because of the handling and I couldn't quite get the clarity of colour, the colours looked very clean until mixed
Then I tried a quick painting the same seeds a piece of natural vellum but omitted the Schmincke, which I didn't much care for. I had to readjust the mixes to accommodate the dark background. It wasn't particularly difficult to create ta decent colour match for the subject. There is no great difference between brands but again the W & N (top) was the preferred paint, The Daniel Smith (Middle) I found had too much Gum Arabic for working on vellum and was a bit less easy to handle as a result. Although paint should never be applied to vellum too thickly, and Gum Arabic can help in achieving a smooth application - too much can crack, so it was difficult to achieve the depth of colour. The M. Graham ( bottom) was good enough but not quite so clean to apply as the W & N.
3 Maple seeds painted on vellum with different brands of paint

Overall I found it made very little difference. I'm happy to work with any of these paints, they are all of very good quality and find I prefer some colours in one brand but don't like it in another. I think as long as you have a good artist quality set of single pigment paints you can make a decent enough painting. Personal preference and technique will influence your choice.

The Palette
There is no perfect palette but as a basic start I think two of each primary ( one warm and one cool) plus one other and a few brights will do the job! If you're a beginner. Learn about those first and try others later when you understand the properties. Here are some of my favourites.

BLUES: French Ultramarine PB29, Cobalt Blue PB28, Cerulean blue PB35 plus Phthalo Blue PB15, Indanthrene blue PB 60, 

REDS: Pyrrol Scarlet  PR255, Permanent Rose PV19, Permanent Alizarin Crimson PR206 and Quin Red PR209, Quin Magenta PR122 Permanent Magenta PV19


Note: I still like W & N Scarlet lake PR 188 too. It's more lightfast than other and not like the less permanent old paints.

YELLOWS: Nickel Titanium yellow PY53, Winsor Lemon PY175, Winsor Yellow P154, Transparent Yellow PY97, Indian Yellow PY153
You can make most stuff from these but I add a few earths too:
EARTHS:Brown Madder PB 206, Burnt Umber PBr 7 ( M Graham) Burnt Sienna PR 101 and Quin Gold PO 49

VIOLETS:Ultramarine violet PV15, Winsor Violet ( Dioxazine) PV23 and Cobalt violet PV 14 I like these for shadows and reflected light


 That's a 'brief' overview, without getting too technical 

Colour Charts for the brands discussed:
Find out more about colour
Books 
Ittens, Johannes., Elements of Colour  or if you can afford or order from the library The Art of Colour
Albers, Joseph. Interactions of Colour
About Watercolour Paint Books
Page, Hilary.  Guide to Watercolour Paint 
Websites