Dyes are substances used for permanently and deliberately staining cloth (or other substances), usually for decorative purposes. They are used to add value to clothing and have been a popular trade good (and therefore form of treasure) for much of human history.
Until the modern period (when dyes have been produced by sythetic chemistry) dyes needed to be extracted from natural materials and varied in price depending on how hard it was to achieve a given colour and the rarity of the organic source - tyrian purple, kermes and saffron were all highly valuable and traded internationally, with more mundane dyes such as woad and madder being produced and consumed locally. Substances such as indigo fell somewhere inbetween.
Natural dyes have historically been extracted from plants (indigo, woad, madder and saffron), shellfish (tyrian purple), insects (kermes and carmine) and fungi (orchil dyes) - source not necessarily being an indicator of price.
Fabrics may be dyed as whole cloth, as unwoven yarn or "dyed in the wool" prior to spinning. If dying whole cloth, patterns may be produced as part of the dying process by resist dying techniques such as batik (where wax is used to protect parts of the fabric from dye staining) and tie-dying (where the fabric is bound into tight lumps to protect it from dye). Other techniques include weaving fabric from a mixture of protected and unprotected yards and then dying it. Many dying processes use a mordant (literally a "biter") to increase the penetration of the dye into the fabric, either by disrupting the structure of the material or by forming a complex with the dye molecules that can bind more easily. Common mordants include salt, urine, tannic acid and various metal salts such as alum (potassium aluminium sulphate). Mordant dying traditionally gives stronger, longer lasting colours that are less likely to wash out, although results will vary enormously in most historical periods.
The other obvious use for dye is to change hair colour as part of a disguise … this is not, normally, the same sort of dyestuff as is used on fabrics.
Game and Story Use
- Good treasure
- Also a good answer to "what does this town do/merchant trade in/box contain?"
- "Travelling dyer" might be a common profession in your campaign - much like a travelling tinker, but moving from village to village dying people's cloth or yarn for them.
- Modern players may need reminding that not all colours cost the same in the pre-modern period (in fact, a lot of people wore undyed cloth or cloth that was only dyed with cheap, local dyestuffs that could be pulled out of a hedgerow nearby) - if they want their character to wear some outlandish colour, a great deal of money may be required.
- Conversely, someone who appears wearing an unusual colour may attract a great deal of interest (or theives) - and if it turns out that that dye is pretty cheap where they come from, merchants may follow them home.
- This brings us back to treasure and adventure hooks - especially if the person in question had to leave home in a hurry, but PCs might very well find themselves hired to escort a speculative dye-buying expedition (or just sent to get some dye/dyed cloth by a patron).
- Synthetic dyes are the sort of thing an alchemist might discover - possibly by accident - or be set to work processing by a patron irked by the endless money-pit of his quest for the philosopher's stone. Snails may turn out to be easier to turn into gold than lead is.
- If characters need to cam up in a hurry, someone with a decent level of herbalism might be able to hunt down a good local plant dye.
- Perhaps some kind of monster yields a useful dye when killed - or something else useful in the dying process like a proteolytic venom which happens to make an excellent mordant.
- Time travelling PCs could probably get good money for modern chemical cloth dyes - you can get a cake of royal purple boil-in dye for a few pounds in the modern era and could probably sell it for its weight in gold in the classical or medieval periods.