Stain Blocker


How can I prevent bleed through on mahogany furniture from the 1920-1930’s?

Never guarantee a finish on this era of furniture. Inform your customers of this issue and steer customers away from using light colors. Many mahogany pieces from the late 1920's to early 1930's have an aniline dye lacquer finish which can bleed through no matter how many times you paint or prime over it. Although ideal coverage over an aniline dye lacquer can never be guaranteed, the following two products have been known to minimize bleed through:

  1. A stain blocking primer such as General Finishes Stain Blocker or Zinsser B-I-N
  2. A shellac seal coat will usually stop most of the bleeding

Note: If you are trying to cover red mahogany with a white you may never be able to stop the bleed through. Stain Blocker is most likely to stop the bleed-through of all options listed above because it was specifically engineered to block the most persistent bleed-through.

Tips from GF:

  1. Never guarantee a finish on this era of furniture. Inform your customers of this issue and steer customers away from using light colors.
  2. Clean the project and apply 2 coats of General Finishes Stain Blocker with a brush, roller or by spraying. The first coat will absorb contaminants in the wood, causing a color change during the first application, and the second will seal the contaminants. More information regarding Stain Blocker here.
  3. Another primer alternative is Zinsser B-I-N.
  4. Use a dark paint color - there are some pieces that will never work with al light paint.
  5. If none of this works, we recommend that you strip and refinish with a penetrating oil stain followed by a clear coat.

Stripping Recommendations:

  1. Use a good quality citrus stripper or a soy gel stripper as they are more gentle than traditional chemical strippers.
  2. Remove any remaining finish with 150 grit sandpaper.
  3. Once you have removed the old finish, wash the piece down with a 50/50 blend of denatured alcohol and water to remove any residual oils and waxes.
  4. Once these stages have been completed, it is safe to use any type of wood stain to restore the original look of the piece.

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*How Can I Improve Coverage When Using White Paint on Furniture?*

A primer is your best defense under light-colored paint.

Another technique to avoid the slight color change that sometimes occurs when applying topcoat is to add 10-15% of the paint you are using to your topcoat. This technique layers additional coats of color over your piece as well as providing the protection of a topcoat. If you don't like measuring, just add enough paint until you can see a bit of the hue in the topcoat. This method works with a brush or a spray gun.

To maintain the full-strength protection of the topcoat, DO NOT TINT YOUR FINAL COAT of topcoat.

Remember, NEVER EVER paint an existing piece of furniture with a light paint without proper preparation AND a stain blocking primer. Topcoats can activate tannins in the wood, or dyes in the previous finish, causing yellow or pink bleed-through. We recommend General Finishes Stain Blocker, which has been developed specifically for upcycling furniture and has proven to be 100% effective when two coats are applied, or Zinsser BIN.

Here is a sample finishing schedule:

  1. Prep clean and sand
  2. Three coats of paint (or four if needed)
  3. Two coats of topcoat mixed with 10-15% paint
  4. One coat of topcoat

VIDEO: How to update or refinish cabinets and woodwork light paint color using a sprayer.

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*My Stain Blocker is Thick, Clumpy and Hard to Stir. Is This Normal?

Time and temperature play a roll in Stain Blocker's thickness and settling in the bottom of the can. What you are seeing is some of the fillers coagulating.

This is normal as long as it is soft on the bottom; it does not diminish its quality or effectiveness. You should be able to reincorporate the contents of the can - use a paint mixer if necessary because it is a thick, heavy product. However, you should not see any hard settle at the bottom of the can.

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