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Q. Dear Umbra,
I live in Halifax, Nova Scotia, where recently our city made a splash when our newly minted sewage system — which had been roundly celebrated for making the harbour swimmable for the first time in years — failed. Now we’re back to flushing it all into the ocean. So when it came time to clean my brushes the other day after painting our front door, I hesitated at the thought of using turpentine, knowing it would end up in the harbour. Is there a greener alternative?
A. Dearest Ceebie,
Oh my heavens yes. That turpentine should never make its way to the Halifax harbor. Turpentine, and all solvents, must be treated as household hazardous waste no matter where you live (the Halifax Hazardous Waste Depot is on Horseshoe Lake Drive, behind the Materials Recycling Facility). For your health, you might also look in to some less-toxic solvents next time you use oil paint; they will also need to go to HHW.
Turpentine is a distillate of pine and other plant resins. It is flammable, volatile, and highly useful in thinning oil paint, cleaning brushes, and zillions of other applications. Unfortunately any substantial contact with turpentine is bad for us and the little animals in our biosphere. In one not very surprising experiment, mice painted with turpentine developed tumors. On the lesser end, it irritates our mucus membranes; on the significant end, eating it can result in tachycardia.
Citrus solvents with the active citrus-peel-derived ingredient d-Limonene have recently emerged as a less-toxic alternative to turpentine. These are sometimes actually made of orange peels, as a byproduct of juice production (see this interesting flow chart). Another source intimated that some citrus solvent is a byproduct of corn ethanol production, with citrus scent added. Either way, they will clean oily brushes and hands, but I don’t think you can make your own at home.
It’s not clear to me how safe d-Limonene is, as there seems to be a dearth of conclusive studies on the matter. It certainly is a mucus membrane irritant, and is flammable and needs to be handled with care. It has not been linked with tumors or tachycardia, so we happily will replace our turpentine and other confirmed higher-toxicity solvents with it. I also found a variety of other even less-toxic brush cleaners by searching online environmental home stores: here’s a promising one.
No solvent should go down a household drain, whether that drain leads to Lake Washington or the Atlantic Ocean. When you need to use a solvent to clean brushes, find a metal can and dedicate it as the dirty solvent can. Soak and rinse the brushes in that can, then use rags to wipe off residue. You might also need a second can of cleaner solvent, then more wiping, then a little water if necessary. You can filter the residue out of the dirty solvent can, to render the solvent usable in future. Both cans and all rags should either be saved against future solvent needs, or taken to HHW. If saved, the cans should be stored in a garage or other uninhabited building, not in a home. For more tips, see my earlier column on disposing of paint.