Why Did My Deck Stain Darken or Turn Black?
There has always been some concern for deck owners as to why a deck stain can darken or turn black in color after a couple of years. There typically are a few reasons why this may occur for any brand of deck stain.
Improper Curing of Deck Stain
When a deck stain does not cure or dry properly it can remain tacky for longer than it should. This can result in embedded dirt, grime, and/or tree pollen. These trapped contaminants can have an increased effect on mold and mildew growth darkening the deck stain. Improper curing usually happens from over applying the stain.
Mold/Mildew Prone Climates
In very hot and humid climate types, mold and mildew can actually begin to form on the surface of a deck stain causing it to appear darker. In extreme cases, mold and mildew can grow below or in the stain further darkening the appearance.
Applying an Inferior Deck Stain
As mentioned, mold and mildew growth can darken a deck stain considerably. Cheaper deck stains lack the formula to fight off mold and mildew. To lower the stain’s cost, some inferior stains contain a “cheap grade” of linseed oil without mildewcide additives to battle mold and mildew growth.
Tips to Avoid Deck Stain Darkening
Most all deck stains are prone to darkening if the right circumstances occur. The darkening effect does not seem to be related to just one brand of wood deck stain but certain brands do seem to have issues more so then others.
Correctly prepping the wood prior to a stain application can certainly cut down the chances of stain darkening. Once a deck stain does seem to have darkened, it should be cleaned or removed completely before a new coat of stain is applied.
Be sure to follow the stain manufacturer’s instructions on cleaning the wood and applying stain. Be careful not to over apply the deck stain which can lead to curing issues. Back brush or use a stain rag to wipe any excess stain or puddles.
Use a high quality deck stain that fights mold and mildew and is less prone to darkening.
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