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moldy leather while wet forming/ stamping

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Cota, Oct 15, 2012.

  1. Cota


    Mar 17, 2012
    Hey guys and gals, I dont post much, but stalk a lot. I am a maker with about one years experience, and am having an issue with my leather getting mildew almost immediately. I live in a very arid part of Oregon, it considered a high desert. I just got a big Tandy order, and it is new leather I am working with, but there is no sign of any mold on the leather at all before I wet it. I even tried wetting it with a water and vinegar solution and it still molds within about 10 minutes.

    Has any one else dealt with this? If so what did you boil the problem down too? Any help is greatly appreciated, thanks!
  2. Patrickknives


    Dec 13, 2006
    I really doubt that you are getting mold, to grow mold in 10 minutes is a pretty much impossible. You can get some discoloration of the surface, I would question the term wetting, you only need a very little water to tool leather. I believe you may be getting some of the chemicals trapped in the leather coming to the surface, I have seen this in Tandy leather which is chemically treated. Try just enough moisture to dampen the upper surface.
  3. Cota


    Mar 17, 2012
    thanks Patrick, we have seen it both when wet forming and just a light spray mist for tooling. its weird for sure, but Im almost sure its mold. Good advice about the chemicals though, Ill do a few more control samples with diff leathers.
  4. mgysgthath


    Dec 15, 2009
    Some pics might help the guys identify whats happening.
  5. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    The leather may have moulded in the past and been bleached to make it salable. The moisture may allow the stains to come out again.

    Do the dark spots and splotches stay after drying?
  6. quint


    Nov 29, 2011
    One of the few reasons I dont buy leather from Tandy anymore. Depending on if its the imported stuff or not it can have various types of coatings used to hide blemishes used on it. Before I have made projects to the point of dying it and when I cleaned it with denatured alcohol it would pull the stuff up and expose various issues with the leather. Very disconcerting.

    Another problem with leather in a retail environment is countless people play with it and who knows what ends up getting on it while there.

    Stacy could be very correct about it being possibly molded before. I use wickett and craig and live in northwest WA and have never had mold happen on any of my leather, even when leaving it dampened in the garage for a day or so.

    Anyways the only thing I could recommend is cleaning it with some alcohol or similar and see if it keeps up.
  7. Horsewright

    Horsewright KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Oct 4, 2011
    A lot of times if you are getting moldy looking green spots and splotches its not the leather. Sometimes it's impurities in the water. High Desert country I'm guessing pretty hard water where you're at. Same deal with me. Try using distilled water. It'll make a difference. You can also get some wood bleach at the hardware store. Mix it with water according to the instructions in a spray bottle. Spray a mist on and watch your green splotches fade away. Rinse by wiping down with a wet paper towel. Take normal precautions with this stuff, it is an acid.
  8. sunshadow


    Oct 2, 2006
    try forming with acetone instead of water, just do it outside away from ignition sources (acetone vapors are toxic, flammable and can explode when properly mixed with air) I wear nitrile gloves and eye protection when acetone forming leather and do it on my back porch, and have had extremely good results (and don't have to worry about rusting the blade I am forming around)

  9. Mahoney


    Mar 8, 2006
    Alcohol will kill mold.

    I have formed using rubbing alcohol (50% or 70% isopropanol) from the drug store. The vapors are flammable so be careful... I have also used cheap high proof vodka to kill odor-causing bacteria in funky smelling leather belts.

    But if you are getting black spots, I would consider one other possibility. Iron + tannic acid = black. How clean is the area where you are working? Any possibility of random grinding dust contaminating the leather?
  10. Mossyhorn

    Mossyhorn Gold Member Gold Member

    Dec 6, 2009
    I've used a water with about 1/5 mix of alcohol. It helps the leather dry much faster. If you happen to have any hardware attached, it will stain the leather if you're not careful.
  11. Cota


    Mar 17, 2012
    Thanks guys all good advice and ill give it a try!
  12. LARRYZ10

    LARRYZ10 KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Feb 6, 2010
    I think you are right about the grinding dust.. I was getting black spots abnd then started stamping my leather in another location and letting them form and partially dry on my kitchen counter. No more spots. But I have a stupid question. How much cheap high proof vodka do I have to drink before I can't smell the funkyness of old leather belts? HA!
  13. Wild Rose

    Wild Rose

    Aug 23, 2002
    Dark green and at times black spots are common with most SA/Mexican import hides such as Tandy mostly sells. It has to do with their tanning process and is not necessarily due to your local water, mold, etc.
    Those kinds of problems with SA?Mex import hides are why the best leather crafters (Paul Long, Sandy Morrisey, etc) only use the best quality veg/bark tan cowhides from sources such as Wickett & Craig, Herman Oak, or RJF Leather - with 51+ years of leather crafting experience these are IMO the current top three leather suppliers. W & C and RJF sell direct (RJF sells shoulders which is a good deal for those on a budget). Herman Oak also sells direct, but has a 10 side minimum - HC though can be purchased in smaller amounts from several dealers such as Springfield Leather.
  14. Wild Rose

    Wild Rose

    Aug 23, 2002
    With respect it may still cause problems with blade staining as well as the long term life of the leather. Using acetone for molding was widely used for a while in the industry especially amongst holster makers back in the 1970's - blade staining problems cropped up at times due to the fact that the acetone forces all of the oils and waxes from the leather and since they also contain moisture problems crept up, but not always right away. Long term life of the leather was also compromised again due to the loss of the conditioners and a chemical change in the leather itself. The leather treated heavily enough with acetone after some years would often break down and even begin to crumble, especially when not cared for properly (that's a problem no matter what, but was increased due to the heavy use of acetone.)
    Anyway just a bit of a heads up and FWIW I do use acetone at time for cleaning the surface of finger prints, etc, but I ONLY use a light swipe or two and never soak the leather.
  15. sunshadow


    Oct 2, 2006
    Thank you for the heads up Chuck, I obviously wasn't aware of these issues.

  16. Wild Rose

    Wild Rose

    Aug 23, 2002
    Page you are most welcome and unfortunately it is one of those things little mentioned or known other than by those of us who have been doing leather for a long time..

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