spxf1113 Posted January 18, 2011 Report Share Posted January 18, 2011 I built the end-grain cutting board, but I just used two types of woods I had laying around: Red oak and Walnut. I finished it with the salad bowl finish without diluting it with mineral spirits. After the 4th coat, I washed the board, the next morning I notices small black spots on the oak. The walnut was fine. I assumed this is due to the large pores in oak. I then sanded it down and started the finishing process over again. I am using the mineral spirits and salad bowl finish method. How many coats should I use? Quote Link to comment Share on other sites More sharing options...
AceHoleInOne Posted January 18, 2011 Report Share Posted January 18, 2011 I believe its the tannins in the oak coming out. This can/is a problem with oaks. Water-based finishes can bring this out also, if you don't seal the wood first with an alcohol cut shellac. Something to do with high PH in drinking water and water based finishes usually have a high PH (well some do). You may have an ongoing problem with this. -Ace- Quote Link to comment Share on other sites More sharing options...
TBaiga Posted January 18, 2011 Report Share Posted January 18, 2011 i get that shellac is food-safe, so would you seal with shellac or dewaxed shellac? Quote Link to comment Share on other sites More sharing options...
AceHoleInOne Posted January 18, 2011 Report Share Posted January 18, 2011 The problem I see since this is a cutting board, the knife will cut trough the sealed surface allowing the water to re-enter the wood. I prefer de-waxed. -Ace- Quote Link to comment Share on other sites More sharing options...
kesac Posted January 18, 2011 Report Share Posted January 18, 2011 I built the end-grain cutting board, but I just used two types of woods I had laying around: Red oak and Walnut. I finished it with the salad bowl finish without diluting it with mineral spirits. After the 4th coat, I washed the board, the next morning I notices small black spots on the oak. The walnut was fine. I assumed this is due to the large pores in oak. I then sanded it down and started the finishing process over again. I am using the mineral spirits and salad bowl finish method. How many coats should I use? I am not sure what salad bowl finish you are using. Virtually all finishes are food safe once cured. Some of those oils, never really cure, and that might be what you are seeing. I use a polyuerethane and touch it up with wiping poly. Nothing lasts forever on a cutting board, if you actually cut on it. Most that I have made are as much for decoration as utility. Quote Link to comment Share on other sites More sharing options...
spxf1113 Posted January 18, 2011 Author Report Share Posted January 18, 2011 http://www.rockler.com/product.cfm?page=5344 I think this is the recommended salad bowl finish on the woodwhisperer video. I guess I will put on a few more coats and see what happens. If it does it again, I may have to start over using a denser wood. Quote Link to comment Share on other sites More sharing options...
Beechwood Chip Posted January 19, 2011 Report Share Posted January 19, 2011 If I understand it correctly, the problem isn't that the oak isn't dense enough or has open pores, it's that the tannin in the oak reacts with water and turns black. Quote Link to comment Share on other sites More sharing options...
spxf1113 Posted January 19, 2011 Author Report Share Posted January 19, 2011 If all the oak eventually changes color, I guess that would be fine. As it was, there where only a few dark areas. I didn't know what it was, so I sanded it and started refinishing it. If there is a way to prevent it, that is what I want to do. Quote Link to comment Share on other sites More sharing options...
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