kates Report post Posted November 16, 2013 I just finished tooling some leather pieces. As they were starting to curl up a bit, I stacked them up on top of each other and placed heavy weight on them overnight. The next day I noticed dozens of small black dots all over the leather! I'm assuming it is mildew. How do I get them out? This is for a client who wants natural looking leather, so staining is not an option. So far I have tried wiping with soapy water, diluted bleach water and saddle soap. Nothing has worked. Help!! Quote Share this post Link to post Share on other sites
Sylvia Report post Posted November 16, 2013 I've never tried it but some say it works. Oxalic acid (wood bleach) You can get it from TruValue or Ace Hardware. Quote Share this post Link to post Share on other sites
Northmount Report post Posted November 17, 2013 I just finished tooling some leather pieces. As they were starting to curl up a bit, I stacked them up on top of each other and placed heavy weight on them overnight. The next day I noticed dozens of small black dots all over the leather! I'm assuming it is mildew. How do I get them out? This is for a client who wants natural looking leather, so staining is not an option. So far I have tried wiping with soapy water, diluted bleach water and saddle soap. Nothing has worked. Help!! Mildew overnight is rather unusual. Chances are some specs of iron got onto the surface and reacted with the tannin in the leather to produce the black spots. As Sylvia says, use oxalic acid to bleach it out. About a teaspoon per pint of water is usually strong enough. In a pinch, use lemon juice. Iron and tannin is the process for using vinegaroon to dye vegtan leather black. You will find it interesting to look up and read about it. Lots of threads here on how to make and how to use. Tom Quote Share this post Link to post Share on other sites
kates Report post Posted November 17, 2013 Before I saw your post about oxalic acid, I tried using diluted phosphoric acid which I already had on hand. It worked! Is oxalic acid less harsh than phosporic acid? I am a little worried about how it will miscolor the leather though, but its much better than it was. So if it was iron mixing with the tannin, how do I prevent this in the future? I have no idea how iron specks could have got on the leather. I didn't see any while I was tooling it. Thanks for all of your help. Quote Share this post Link to post Share on other sites
Northmount Report post Posted November 17, 2013 (edited) What are you using for a mallet? If it is a steel hammer, it's knocking little flakes of metal off your stamps. Make sure to use a mallet made of the right materials to avoid damaging your tools. Any filing, sharpening, sanding, wire brushing or similar activities involving iron based material could spread fine bits of iron over various surfaces. Need to keep the leather, tools, and work surfaces clean. Keep anything rusty away. Another source is iron in your water. Try distilled or deionized or reverse osmosis treated water. Do you have rust stains in your sink where your water drips? Another is contaminants in the leather that reacted when dampened, but not likely as it should have shown up in the tanning and finishing processes. Phosphoric acid is fairly strong, so could do more than you wish. Should be rinsed off and neutralized. Tom Edited November 17, 2013 by northmount Quote Share this post Link to post Share on other sites
