The coloured pencil core of non-soluble pencils is made with either wax or oil to bind the pigment to the paper - or more usually a blend of the two.
The two types of pencil are intermixable when used dry. Oil based Pencils are generally made in Europe (outside the UK) and are often slightly harder than pure wax. This is not a problem and the oil pencils work very well. Many oil based pencils contain some wax, so the exact formulation is often confusing to the average buyer. To understand more about this topic, see the page linked here on Wax or Oil.
Very heavy layering of the type with a wax pencil core, on paper, can result in a grey ‘wax bloom’ starting to appear on the picture surface. This obscures the sharpness of the picture and can be annoying if the picture has to be removed from the frame to correct it. This bloom does not occur with oil based pencils. It usually happens in hot and humid climates.
Wax bloom can be removed and there are sprays available in the USA to protect the wax surface from developing the haze, but most users of European made pencils will never have to worry about this problem. The sprays are not generally available in the UK for this reason.
BUT if you want a SOFT pencil that is NOT subject to wax bloom, Caran d’Ache make a soft wax/oil based pencil (Luminance) in Switzerland. They are fully lightfast, notably more expensive than all the others, have a very high pigment level and are manufactured by a special process to avoid wax bloom. The 72 set is sold in the UK at a recommended price of £270 but is available on the Internet for around £170 and less.
The colour component of the pencil colour strip, the pigment, is broadly the same as the pigment found in any other art medium.
The pigment may be made from a traditional natural source ( e.g. Ground earth - Umber , Ochre etc) or it may come from a chemical source (such as Phthalocyanine or Quinacridone etc), usually from a result of the oil processing world and the development of organic compounds that stain and colour.
In addition, a coloured pencil core will contain gums and possibly clays to give strength to the core, There will be fillers to adjust the colour to give pastel shades, and the waxes and oils described above which enable the colour to move smoothly and stick to the paper. There is a whole topic on the use of waxes and oils in a later section which you can refer to.
When buying the wax type, non soluble pencils, look for transparent colours which will layer well and enable a greater depth of colour as layers of different pencil are laid down. This enables Coloured Pencil artists to achieve a painterly result with accurate colouring.
The natural pigments used in soluble (Aquarelle) pencils can be used in the same way as those found in artists watercolour paints, as many will lift from the paper or react together to form a granulating mixture that develops a look of dappled leather or stone on the paper surface.
Other modern organic pigments can be more permanent and more staining and react like student quality watercolours.
Faber-Castell ‘Albrecht Durer’ Aquarelles act more like watercolours and many colours can be lifted from the paper if they are not left too long to dry and set.
There is also the Albrecht Durer Magnum pencils which are both lightfast and permanent on the paper, after water has been applied.
The pencil core of Derwent Inktense are similar to inks. They are permanent once wet, and can be used for silk painting and (they say) the fabric can be washed in a warm wash. Fabric should be natural (non-synthetic) and a fabric medium is recommended to ensure the colour does not bleed into the fabric where it isn’t wanted.
There is a very good article here (Sept 2017) from Derwent, which covers the subject well. Inktense are also sold in block form. They are very strongly pigmented.
Watersoluble coloured pencils are acceptable for most international competitive exhibitions provided that they are used entirely dry.
They are NOT accepted when the pencil core has been dissolved with water and they are then classed as Mixed Media. Don’t blame me! I don’t write the rules and I don’t understand the thinking either. I suppose that it is some sort of improvement on the position a year or so ago, as Pastel Pencils are now acceptable as a component of ‘Mixed Media’ and they used to be banned altogether from Coloured Pencil competitive exhibitions.
The differing pencil core can have an effect on the price. When I first wrote this page 10 years ago, I said that you could expect to pay around £1 a pencil for quality pencils sold in sets, But these days (early 2019) most good Artists quality pencils are around £2, and some of the top brands come in at nearer £3.00 per pencil
You can get a good student quality coloured pencil for around £1 a pencil. and in the last few years sets of pencils imported from Eastern Asia have been on sale at 50p per pencil. Price is no longer the guide to quality in the lower price levels of the listings as we have seen good student pencils at 50p and poor quality ones at £1.50.
It is always better to go for a well known named brand where the manufacturer has a reputation to keep up. and buy from a source where you can return any faulty goods.
Single pencils from quality brands sold by retailers and specialist internet sellers will cost around £2 , but there are exceptions and occasional deals. These loose pencils are commonly referred to as ‘Open Stock’ and are invaluable for re-stocking your supply of the most used colours.
If you are paying below £1.50 a pencil and it is not an exceptional or special offer then it is likely that you are not getting artist quality but are in one of the ‘Student’ ranges with more clay or binder in the pencil core and less pigment. There is nothing wrong with this, but the artists quality, top of the ranges, will give you the most reliable results.
If you are looking for a full set of - say - Polychromos, which market at an RRP around £200 for a box of 120 pencils and sell singly for around £1.60 each, you may pay anything down to £150 or even less in a very special Internet deal. (Though prices of European manufactured pencils have tended to rise quite a lot in the last years as the value of the £1 has changed against the Euro. We used to pay around £100 for a box of Polychromos when I bought mine 10 years ago. The price at Amazon in February 2019 is around £140.
Coloured Pencils tend to be much cheaper in the USA where the market is very big and more competitive, so buying them on a USA visit makes sense - especially if you are visiting relations who can mail order them in advance for delivery to a US address for you to collect.
Take care over buying mail order from the USA for delivery direct to the UK, as shipping can result in a compulsory VAT bill on the import as well as Import Duty and high shipping charges. You also have the problem over resolving queries over damaged or faulty goods - much easier if the retailer is in your own country!
Derwent sets can be found from time to time in selected retail outlets at very special prices and can be worth buying even if they are not immediately needed.
The set of 72 Coloursoft can sell at prices as low as £75 on Internet sale with a recommended retail price of over £135. Keep an eye on offers at shows where art materials are sold.
HOWEVER, It pays to know the ‘going price’ - check the Internet before you attend the show, so that you don’t pay more for a ‘special offer’ than can be paid normally over the Internet.
Look out for old designs that have been replaced (though care will be needed over old formulations of pigment - see the ‘lightfastness’ topic) These deals can be very cheap, but may not be as good a buy as they seem if the old formula of pencil core is a poor one.