00101 Posted January 30, 2011 Report Share Posted January 30, 2011 I'm making a cutting board, and its ready for the finish, but how far should I dilute normal poly to get the the consistency of the half diluted salad bowl finish that marc used? Like 1:4? Quote Link to comment Share on other sites More sharing options...
Ben H Posted January 30, 2011 Report Share Posted January 30, 2011 Why are you putting poly on a cutting board? I'm fairly certain that's a very bad idea. "Normal" Poly has synthetic resins (lab made), while the salad bowl finish is made with natural resins (NOT lab made). Maybe it's just me, but I wound't want my food being cut and chopped on a board with a chemical finish. Someone please correct me if I'm wrong. But from what I understand, While poly is a "form" of Varnish, a traditional varnish is made with natural resins. Quote Link to comment Share on other sites More sharing options...
00101 Posted January 30, 2011 Author Report Share Posted January 30, 2011 Well, looking at the msds, the only routes of harmful exposure are getting sprayed in the eye with it, touching it while its not cured, and the obvious inhalation. It says nothing about ingesting it, although on all of this, none of it specifies whether or not it is talking about pre-cure or post-cure. I did a little research and found that polyurethanes are organic chemicals that are synthetically mass produced. I have seen advice that it can be put on wooden toys, I also have it on an old cutting board I made a while back, and so far nothing has happened to any of us, so I assume its fine. But still, the salad bowl finish is a wiping varnish, and Marc dilutes it to about half, so I'm thinking 1:4... Quote Link to comment Share on other sites More sharing options...
Bombarde16 Posted January 30, 2011 Report Share Posted January 30, 2011 "Natural" is a relative term, here. Undoubtedly, if sufficiently concentrated and pumped into laboratory rats in the state of California, even salad bowl finishes would be found to be carcinogenic. Heck, you could probably find a lab somewhere in California that's working on the teratogenic dangers of dihydrogen monoxide. Out in the real world, once cured, finishes are inert and harmless. I would have no objection eating off a cutting board sealed with thinned out urethane or feeding my family off such a board. Just be sure that you're soaking the board through, standing it vertically and wiping the excess off the surface. The goal is to fill the wood fibers with cured finish but NOT to build any sort of a film. Happy boarding. Quote Link to comment Share on other sites More sharing options...
Robert T. Posted January 30, 2011 Report Share Posted January 30, 2011 The dangers of dihydrogen monoxide always make me laugh. Quote Link to comment Share on other sites More sharing options...
Ben H Posted January 30, 2011 Report Share Posted January 30, 2011 I love P&T. Quote Link to comment Share on other sites More sharing options...
HoboMonk Posted January 31, 2011 Report Share Posted January 31, 2011 1. "Poly" is a generic term. Wood finishing products that contains polyurethane can range in concentration from as little as about 5% to greater than 20%. Also, they can have a myriad of other ingredients - there is no rule about the recipes. Most often, polyurethane resin is used in conjunction with other resins such as the alkyds. 2. "once cured, finishes are inert and harmless." This is a frequent Internet echo that just isn't true. 3. Putting a film finish on a cutting board isn't a good idea if you plan on actually using the board. A film finish, food safe or not, will suffer. It's best to use a food safe non-drying finish such as mineral oil purchased from your local pharmacy. (clinical chemist and toxicologist) Quote Link to comment Share on other sites More sharing options...
Bombarde16 Posted February 3, 2011 Report Share Posted February 3, 2011 Agreed that a non-toxic finish is ideal for anything that will contact food. But is this to the exclusion of anything that isn't marketed as non-toxic? It's fine and accurate to propose that such and such a finish (i.e. mineral oil) is harmless. But the hangup is on the logical corollary to this: namely that other cured finishes are therefore lethally toxic. I believe this was the point of Ben's question. 2. "once cured, finishes are inert and harmless." This is a frequent Internet echo that just isn't true. OK, you aren't just going to leave that without an explanation, are you? If they aren't inert and harmless, then under what circumstances or levels of exposure are they active and harmful? Quote Link to comment Share on other sites More sharing options...
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