I am currently experimenting with colored mulch used for gardens, as I am interested to know how to formulate my own colorants to color wood chips. I have obtained some quantities of the main ingredients needed:
1) Red iron oxide color pigment
2) Polyvinyl acetate pva emulsion as binder
However, I'm stuck with the proportions needed to mix the raw materials together. I've tried using several mixtures (including adding water), and each time I soak my wood chips in the solution. First time I soak the chips, the colors don't stay on very well. I've had to dry the chips, and then soak them into the solution again for the second time before I get a satisfactory color. Here's my mix of chemicals that I've been dabbling with...
(My mixture: 2 litres water mixed with equivalent to 4 tablespoons iron oxide and 3 tablespoons pva emulsion)
I have a feeling I might be adding too much water but can't be sure... Am desperately looking for a way to soak the chips just one time, and having the colors stay on perfectly without using too little or too much color pigments/binder. Can any tell me what I'm doing wrong and advice me as to the proportions that need to be added to make a good 'aqueous' solution? I would gladly appreciate if anyone can point me in the right direction. Pls help.
Btw, the polyvinyl acetate emulsion product label says something like 'polytron 50' which I assume to be something about being 50% solids? Anyway, thought this info might be useful
Good fine synthetic red iron oxide (99%+ pure) is a very strong pigment and durable, since ultraviolet light and moisture do not affect it. It is not cheap, but a little goes a long way. Natural oxides are cheaper, not as strong or durable and contain some impurities. The good oxides are not cheap, and harder to get unless you deal in very large amounts (over 10 tons). - Same pigments are used in some magnetic tapes and in some paints. Playing with them is like playing with colored dynamite, so you have to be very accurate
We used synthetic oxides (red, yellow and some tans/browns) to color concrete products. After a week or two of production our employees would throw away every bit of clothes they wore to work and hope the pigment would wear off the skin in a few weeks. That is not the same pigment that is sold to tint mortar.
I suspect the problem is getting the wood dry enough to absorb the pigment because the pigment is too permanent to fade.