Transparent Stain Removal
Transparent wood and decking stains are the easiest to remove. Very lightly pigmented, these stains are the easiest to remove as the stripper has no difficulty penetrating and dissolving the old coating. Expect 95% removal in most scenarios.
Semi-Transparent Oil-Based Stains
Semi-transparent stains can be slightly more stubborn to remove. Stains strippers still work very effectively on removing these types of stains. In most scenarios you would expect 90% removal or more.
Water Based Semi-Transparent Stains
Water based acrylic stains can be difficult and in some cases impossible to remove. The range of removal will vary widely. For example: Defy Extreme Semi-transparent stain is deep penetrating and does not film on the wood. You would expect 90% removal. Behr semi-transparent stain films on top of the wood. Film-forming stains are much more difficult to remove as the stripper will have difficulty penetrating through the coating. For Behr Stains you will probably be able to remove about 50-70%.
Semi-Solid Oil-based Stains
Penetrating semi-solid oil stains can be removed fairly easily. Expect removal of about 80-100%. This can vary as the brand being removed and the amount of coatings.
Water Based Semi-Solid Stains
Extremely difficult to remove if not impossible. These stain types are basically paints.
All Solid Stains
Deck Stain Strippers will not remove solid (opaque) stains effectively or easily for either a water or oil based stain.
Overall Effectiveness of Deck Stain Strippers
In general the better the stripper can penetrate into the wood, the more effective it will be. Penetration depends on the amount of pigment and the type of stain. Oil based stains are easier to remove then water based stains and solid colors or paints are nearly impossible to remove.