I do a craft thing — I make rosaries with nylon cord, faceted plastic beads, metal medallions and crucifixes. I don’t sell them; I just leave them in the church vestibule for people to take them free.
To make cord rosaries right, the tips of the cord should be stiffened for easy threading- through the beads, medallion and crucifix. I’ve tried a couple of things and they’re okay, but yesterday, someone told me that polyurethane does the job extraordinarily well. “It makes a spear of the cord,” he said, so I want to give it a try.
My concern is the potential toxicity if people — especially children — put the cord in their mouths. Inhaling polyurethane is harmful as the directions on the can plainy state, but once it’s applied and has dried, what then?
I went to acehardware.com’s website, but they don’t have any** Contact Us** links.
IANA Hazardous Materials Expert: After reading several of the MSDSs for polyeurethane products, I would suggest that you not inhale any smoke, and wash away any dust or residue . That covers all the dangers I saw listed. If you can get ahold of Ace, ask them for the MSDS for that specific product. They are almost certainly legally required to have it on hand.
Unfortunately I know too much, though a mixed and inconsistent bag, about the dangers of polyurethane, though I don’t exactly know what you are asking.
Urethanes are generally formed by crosslinking some base compound (I think it’s called a “polyol”) with a crosslinking agent, the crosslinking agent being an isocyanate. Isocyanates have active groups that look like -N=C=O where the double bonds can easily break and grab something else (thus their utility). This makes them dangerous for humans. Our immune systems can “seroconvert” and recognise their chemistry as dangerous, and thereafter we can overreact and even die when exposed to them.
I got exposed to toluene diisocyanate in an industrial setting about 22 years ago and have had chronic bronchitis since. The people of Bhopal (sp?) India were exposed to an isocyanate and many died. So there’s certainly a real problem with these things.
Isocyanates get consumed in the crosslinking process, so the raw ingredients are more dangerous than the final product. However, crosslinking never quite finishes, and there are always a few spinster molecules hanging around at the end. I’m not sure how you make sure what you want to do is safe - but, then, it may be safe, I don’t know.
[QUOTE=Napier]
Unfortunately I know too much, though a mixed and inconsistent bag, about the dangers of polyurethane, though I don’t exactly know what you are asking.
Say I apply the polyurethane to the cord, which dries, and I use the cord to make a rosary. Then a kid takes the rosary from the church and somewhere along the line puts the cord in his mouth. Can this exposure to the polyurethane be poisonous to the child?
You can get foodsafe polyurethanes, but these folks seem to think that the danger of just about any wood finish is negligible.. However, if you want to be utterly certain, you could try a foodgrade shellac. (OK, it’s made from beetles, but it’s not poisonous.)