Monday, August 11, 2008

Answer for Dianne

In a comment on the last post, Dianne asked what type of alcohol is used to extract color from wood.

It doesn't really matter what kind of alcohol you use; any will do. It just depends what's available for the least money. I use the type of alcohol that is sold by the big-box DIY store in 1- or 2-gallon jerrycans for use as a cleaner, lacquer thinner, or stove fuel. This "denatured alcohol" is ethyl alcohol with some methyl alcohol mixed in to make it non-consumable (causes blindness or even death if ingested). Some folks swear by moonshine (illegally distilled corn liquor), others use cheap vodka or Everclear (a high-alcohol-content beverage similar to moonshine - it's legal in some US states, not in others). Rubbing alcohol from the pharmacy is usually too expensive, because it's sold in small containers, but it works too.

The alcohol draws out more colorant from the wood chips than plain water, but it takes time. I've got jars of various woods that have been sitting in my studio since March. The liquid in the jar keeps getting darker as the process continues. They'll get used whenever I get around to another wood dye splurge - one of which is gonna be soon, because I need to dye some weft yarns for the upcoming wood series scarves. There is no spoilage problem, because the alcohol inhibits anything that would cause mold to grow, so the jars can sit indefinitely.

It's possible to reuse the wood chips. I did some dyeing with walnut chips extracted in alcohol. Instead of discarding the chips, I strained them out and put them back in the jar with fresh alcohol, which is now as dark a brown as the first extraction. I'll keep reusing them until there's no more color in there. With some woods, the second and subsequent extractions will be not only paler but also a different hue, because the alcohol pulls out different colorants at different rates.

I've used alcohol extraction on materials other than wood. There's a jar of finely ground madder root in a jar in the studio. The first extraction was the classic rusty madder orange. On the second extraction from the same material, the liquid is more red. Eventually, I'll do a third extraction, and hope that it draws out a true red.

Okay, madder root is pretty close to wood in structure, so it's not too much of a stretch to see that the alcohol extraction will work. The jar of lichen is more of a stretch - because lichen is a symbiotic construct of fungus and algae, it's really unlike wood in structure. The true test will be the dyebath, and subsequent light exposure and washing, to see if the chartreuse of the liquid bonds with the fiber/mordant and if it really is light- and wash-fast. Stay tuned!

P.S. I've also got some jars of the type of lichen (various umbilicates) that are extracted with a solution of equal parts of ammonia and water. Unbelievable purple color in those jars! That'll be another exciting dyebath. Smelly, but exciting...

P.P.S. I've written up instructions on using the alcohol extraction method, and plan to put 'em in a PDF on my website. I'll post when that's available.

1 comment:

Dianne said...

Thank you, great info. Thought I'd like to try some of our native timbers sometime, rimu, kauri.
So much to try, so little time!