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A Little About Blotching

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  • A Little About Blotching

    This article on the dreaded problem of "blotching" on woods appeared in the "New Woodworking" magazines in the UK.

    I thank, NWW for allowing me to pass on this information to those who are interested in preventing or reducing this finishing problem to our projects.

    My thanks to SSW&C for allowing me use the article on the forum.

    I hope it uploads, otherwise I go to plan #2 - BobD please stand by.
    Attached Files

  • #2
    My friend, I think a washcoat is a coat of thinned finish that's applied to bare wood to partially seal the surface before a stain is applied. It keeps the stain from soaking into the wood and causing blotching. It works well on woods like alder, aspen, birch, cherry, and pine. The washcoat is usually made with shellac, vinyl sealer, or glu-size; but you can use other finishes as long as the stain does not dissolve it. To avoid problems, don't use an alcohol reduced dye with a shellac washcoat


    • #3
      Mr Cool,

      I think you better read the article again.

      You could also use your "clear coat" as a wash coat/ sealer. If your clear coat is Lacquer, Shellac, Varnish, Polyurethane, even your Oil Finish could be used as long as the stain is completely dry.

      In some cases, it may take more then one application of the sealer, like on open grained woods.

      Making up samples will tell you whats best for each wood.

      As far as any type of stain goes, if your spraying even with aerosols there is no problem with any stain. its the wiping or brushing coatings that could be a problem, in that case wipe or brush in one direction only, allow for drying, and then wipe or brush in the opposite direction to seal the woods.

      A simple "sample" will tell you what to do for all your materials.
      Last edited by MacS; 03-30-2007, 06:28 AM.


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