General Notes

Leather is dyed to enhance the appearance of the leather but without obscuring its natural tactile appeal. Aniline water based dyes or spirit dyes are preferable, as they hide nothing of the natural character of the leather, leaving visible scars, scratches, growth marks and the grain which almost all skins have. The wonderful feel of the leather is in no way impaired. It is quite possible to paint the surface of leather with pigment and acrylic finishes but there seems no point in covering up the individuality of the skin and spoil its tactile quality.

Leather is a natural product varying in composition, differing fibre structure and porosity. Some leathers are tanned differently to what we are used to and some have different finishes and coatings. Even two similar skins cannot be relied upon to give exactly matching results.

Bookbinders in the main use vegetable tanned leathers which are excellent for dyeing and calf is especially receptive. I like to think that dyeing leather is an art not a science as variations in materials, conditions and the craftsman's touch have a direct effect on the results.

General Tips

• Calfskin takes dye very well but good results can be obtained with goatskin. However, goatskin can be obtained in a very good range of colours from our suppliers. It should be pointed out that the dyestuffs for these are mixed with other substances such as casein.
• Water based dyes are regarded as being more lightfast than spirit stains. This belief is shared by Hewits and the Leather Conservation Centre and they both market water based dyes. This is backed up in literature by craftsmen in trades such as cabinet making and woodturning.
• Spirit dyes are fast when wetted with water but can shift if they come into contact with a spirit or oil based substance. Water based dyes will shift when wetted unless treated in some way. Both should be finished with a wax-based coating/polish.
• It is advisable to dye leather after paring but before covering the book.
• Always wear gloves and an apron or old cloths. Wear a mask if using dye powders or when spraying.
• Try to ensure the leather you are going to dye is free from grease such as sweaty fingerprints and has a surface free of traces of paste or glues.
• It is advisable to dampen (not soak) the surface of the leather before applying the dye. This will assist the dye to permeate the skin but even more importantly aid you to get an even finish without streaks. Spraying with an airbrush will give a very even finish but I am wary of using an airbrush with dyes mixed from powders. I feel vulnerable to blockages in the nozzle.
• Apply dye with a well-charged wad of cotton wool with a circular motion. I feel if worked in straight lines any streaks are more noticeable.
• As a general rule you get more striking colours by starting with a very pale leather such as fair calf or fair goat.
• The colours of both water based dyes and spirit dyes can be mixed to achieve a different shade.
• A water based dye will penetrate deeper into the skin than spirit dyes but with both, it makes sense once the surface has dried a little and gone past the very wet stage, to turn the leather over. The idea being that the leather will dry from the reverse side which is now uppermost, pulling the dye further into the skin.
• You might try a dye bath for an even finish especially with a water-based dye. The dye may penetrate further into the leather. However, excess dye powder and sometimes salts may dry on the surface but these can both be buffed off.
• If the leather is soaked, stop there's no point in applying more dye. It won't be taken up.... better to wait till dry and then start again if a deeper colour is required
• For restoration work you often have to dye new leather to match the existing board leather. You may invest in a range of skins, choosing one nearest to the required colour and altering it with the application of a suitable dye.
• However, if your use of leather is infrequent then maybe it is more practical and economic to buy one skin of faircalf / fairgoat or a light colour which can be dyed to any of the colours available.

Water Based Dyes

Hewit's Aniline Leather Dyes - These are perhaps the most readily available to the bookbinder, each of the 10 colours coming in a useful, small 50ml pot as well as a larger 500ml bottle. So if you only want one colour you only have a small outlay.

The same dyestuffs are used by Hewits in the tannery but perhaps in a slightly more technical manner. To ensure a good take up of the dye and to create an even finish over the entire skin, they use certain procedures, which we cannot do on a smaller scale.

As a water-based dye they do offer a greater degree of control than the more aggressive spirit based dyes and being water based may perhaps permeate deeper into the skin than a spirit dye. The nature of the leather changes very little after the application of Hewit's dye and remains supple.

The use of Hewit's 'Dye-Fix' is recommended. This is a fixative that is applied to the stained leather when dry to make the colour permanent.

Hewits do not give a set formula for the mixing the dyes merely stating that the intensity of the colour can be determined by the strength of the solution used.

Tips

• Mixing. To make up the dyes for most of the colours including all of the browns, I would suggest making up the dyes using 1 level teaspoon to 50ml water. Mix the powder to a paste with a little extra cold water, then add the 50ml boiling water.
• However, some of the colours need to be made to a weaker solution. If made too strong, bronzing can occur and, especially with the bright red, it can turn to jelly.
• Try using the mixture hot (but not boiling) for more effective results.
• Too many coats seem to make the colour less lively.
• If bronzing takes place after the dye is applied to the leather, wipe off lightly with cotton wool wetted with milk.
• Most of Hewits dyes are compatible so you can change the shade by adding a smaller quantity of a different colour.
• Use Dye-Fix. It really works

The Leather Conservation Centre - Sellaset Dyes The Sellaset range of dyes marketed by the Leather Conservation Centre, are excellent. Unlike Hewit's dyes, you really need to buy the whole Sellaset package which costs about £70, but there are some advantages.

The kit consists of just three primary colours plus brown and black together with Tinofix and the colour mixing charts.

The dyes are already in a liquid form, albeit very concentrated, so there is no mixing up from powder. The charts enable you to decide what proportions of the basic colours you need to mix to arrive at the colour you want. You do need to be very accurate in measuring these out to get an accurate match but almost any colour can be achieved using only three of the range of five dye colours. It is suggested that distilled water is used in diluting the colours but there seems to be no problem with the solutions aggregating or settling out if they are kept for a time.

Their fixative is known as Tinofix. I reckon the package will last me about 3 lifetimes!

Spirit Based Dyes

Many binders prefer to use spirit dyes for a number of reasons.

• They are quick
• The colour is intense
• They dry relatively quickly
• They are wet-fast

However, some of these qualities can be viewed as drawbacks, depending on your point of view.

Being immediate and intense can mean that you don't have the degree of control that you do with a water-based dye. The problem of wet-fastness as when using water based dyes is not an issue. Spirit dyes tend to make the leather a little stiffer, less supple and the beautiful smell of leather is lost to some extent.

I use both water-based dyes and spirit dyes and believe it's a case of 'horses for courses'. I tend to use water-based dyes more for restoration work and perhaps spirit dyes for more modern binding.

Fiebings Spirit Leather Dyes (available from numerous online sources) - These come ready mixed in a good range of colours and are available in small quantities. There are a few extra products from Fiebings Dye-prep, De-Glazer and the Dye Solvent that they recommend you use for best results.

However, if you are using a good clean leather you don't need the first two. As a solvent , you can use methylated spirits. It doesn't need to be IMS, just the ordinary pink methylated spirits as the pink colouring is so dilute it has no effect on the outcome.

Tips

• The dyes can be mixed to achieve a different shade.
• The ready mixed spirit dyes are quite strong but can be thinned with IMS, methylated spirits or isopropanol. Even pastel shades can be achieved if diluted correctly.
• Do dampen the leather before dyeing.
• Ensure you have plenty of arm room to allow you to work reasonably fast. Use a large wad of well-charged cotton wool in broad strokes with a circular motion to prevent streaking. Don't dab it on.
• If streaks appear or you miss a bit, don't attempt to touch up. Better to use a more dilute dye and give a second coat which will hide the earlier imperfections and make a richer colour.
• An alternative method of applying is to use an airbrush. Really good for giving an even finish especially for larger areas, it may be advisable to thin the dye further and build up layers of dye slowly. Do not set the spray too fine otherwise much will be lost through evaporation. Make a spray booth from a large cardboard box but try to use in a well-ventilated area.
• Spirit dyes evaporate more quickly than water-based dyes. Remember the tip about turning the leather over to encourage the spirit to evaporate through it pulling the dye further in.
• Methylated spirits is miscible with water so you can try to get the best of both worlds by mixing to aid penetration.
• When dry, buff the surface to remove excess surface dye to give brighter results and finish with some form of protective wax polish.
• It is easy to contaminate a spirit dye and alter its colour, perhaps by using an applicator which had previously been used with a different colour. It is a good plan to decant a small quantity into a small container and use from that to ensure the whole bottle is not inadvertently contaminated
• If you flex and manipulate the leather whilst the spirit dye is drying it will help it remain supple.

John Jameson - is a bookbinder with many years experience. He has owned and run Cotswold Bookbinders in Gloucestershire in excess of 20 years. John specialises in Book Restoration and bespoke presentation books for special occasions. John can be contacted at john@cotswoldbookbinders.co.uk