I’m wondering what kind of heavy metals or other elements have been commonly used in clear finishes over the years. I’m interested in this question specifically because I’m looking to salvage some old hardwood flooring for a new house I’m building for my family. The old finish will become fine dust when the floor is sanded, and obviously I want to avoid introducing something poisonous into the house just before we move in.
Was lead ever used as a drier in varnish or other clear finishes? I’ve also heard that for a while arsenic was put in furniture finishes in order to twart mold or other organisms.
Thanks for the help.
Replies
Smasher, at one time, large quantities of lead were used in opaque paints (mostly as a whitening pigment)...and heavy metals of various kinds (including arsenic) were used as driers (Japan drier) for "boiled" linseed oil, which was, in turn, incorportated into some of the old varnish recipes.
I'd recommend that you give one of these salvaged floor boards a good rub down with denatured alcohol and see if it softens the old finish. Shellac was the most common finish used on floors (and it's still one of the best)...so, if alcohol softens it, you're home free...since the film left by thoroughly cured shellac is non toxic.
...Frankly though, if you wear a respirator while planing or sanding this stuff and then ventilate the house real well, I doubt if the residue left from an old varnish would be all that dangerous (old paint would be a different story.) The fact is, your new house is doubtless loaded with plywoods, the fresh adhesives in which are probably giving off formaldehyde...While the drying solvents in other adhesives and plastics used in plumbing, electrical wiring, fibers in some insulations etc. etc. aren't all that healthful either...In fact, you might want to open all the windows and hold off movin' in for a couple of years. :O)
Edited 9/23/2003 5:53:48 PM ET by Jon Arno
I'd second everything that Jon said. If I were to sand this old floor, I'd empty the room and close it off with plastic and towels on the bottoms of the doors. Then, I'd sand using good dust protection and vacuum thoroughly. Then, maybe, wipe off horizontal surfaces with a damp towel. If you don't confine the dust well, you'll make a real mess of the house and the significant other may withhold certain considerations anyway!
Mike, your precausions certainly ought to be adequate, if he chooses the install-and-then-sand approach to this project.
Personally, if this old flooring is plenty thick, with a lot of wear surface remaining above the T&G, I'd opt for planing it down prior to installation. On a nice day, he could do the planing outside and completely avoid the contamination problem. Also, it's a lot easier to push it through a planer than to jockey around one of those floor sanders over who knows how many coats of old varnish...especially when the abrasive disks keep getting clogged up with varnish resins. If the flooring is installed after planing, it should need only some light sanding to even it up and prepare it for a nice glass-smooth finish.
Another option we haven't introduced yet (if he can't afford to loose much thickness) would be to install the flooring as is, then use a chemical stripper. This would entrap most of the potential contaminants...at least there wouldn't be any airborne dust that might contain heavy metals to worry about...but I still don't think even the most noxious of the old "pre-Liberal" ( pre-OSHA protectionist legislation) varnishes contained enough heavy metal driers to be all that dangerous when all you're dealing with is a little residue resin dust that might remain after a thorough clean up. Also, whatever toxic solvents the old varnish might have had would certainly be long gone...so, I don't think we're dealing with a serious problem to begin with.
I'd be much more concerned, if the old finish was a pigmented paint. There was enough lead per gallon in some of those old paint formulas to sink a garbage barge.
Once upon a time I dealt with a similar problem by reinstalling finished surface down. I was lucky with respect to nail holes, perhaps you might be too? Running them thru a planer seems real good idea, too.
I agree with the notion that pre-planing would reduce the in-situ sanding requirements. I am making and installing my own hardwood strip flooring in my new home. A friend came over one day and examined a floor I had just finished nailing down. He was surprised that it was sanded already. It wasn't! Having come off my planing process, the lumber was much more consistent than the commercial stuff and hence will certainly reduce sanding. There is a lot to be said for that.
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