Deck stain blotchy?

There are two reasons deck stain can turn out blotchy. The most common reason is overapplication of the deck stain. The other reason most people have their deck turn out blotchy is that they did not prep the deck properly before applying the deck stain.

Why does overapplying deck stain make it blotchy?

Over-applying deck stain keeps it from soaking into the wood properly, but it still dries somewhat. The liquid sits on the wood, unable to penetrate, particularly with oil-based deck stains. This means that parts of the deck could be dry while other areas are blotchy and tacky. This is the result of not applying the deck stain evenly and using too much deck stain.

Why does prepping incorrectly make the deck stain blotchy?

Prepping correctly before applying deck stain is important because without it the stain cannot penetrate the wood, beautifying and protecting it appropriately. Prepping should include sanding, cleaning, and checking the weather to ensure there will be no rain in the next 24 hours. Proper prep to avoid blotchiness is different for different situations.

More information on how to properly stain a deck

For more info, see our Deck Stain Facts section with over 150 simple Q&A articles that answer all the questions that you have regarding deck staining, cleaning, and prep.

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Scott Paul ~ Restoring Wood & Decks Since 1993 Owner

As an article and comment contributor to the site, Scott has been around the pressure washing industry since attending college. In 1993 he started his first company called Oakland Pressure Wash specializing in exterior pressure washing and deck staining. That company evolved into OPW L.L.C. shortly thereafter concentrating more on exterior wood and deck restoration. Scott and his Deck Cleaning Michigan company have restored over 10,000 decks in the Metro Detroit area since the early years. He has become an authority in the deck restoration industry and has contributed to numerous wood restoration forums and informative sites. All the products he suggests through this site are sold through online sites and in retail stores, allowing the consumer to choose their own means of purchase. Scott’s eCommerce sites do sell many top brands he endorses and if you appreciate any of the help he has offered then feel free to purchase from one of them.

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Benny

1 year ago

I have a brand new deck (built about 6 months ago before winter). When I went to buy deck stain now that the weather is getting better (I purchased water based semi-transparent in white) the person told me I should fill in any cracks with wood filler. BAD IDEA. It went on like peanut butter so after some research I found I needed to sand off the horrible abomination. Since the entire deck wasn’t covered with the wood filler, I only had to sand certain parts and it all came up but required 36 grit belt sand paper to get it off. My question is can I now just sand the entire deck with 80 grit or does everything else also need to be sanded with 36 first and then stepped up in grit? I obviously don’t want blotchy stain but read on some sites that the sanding only matters for smoothness and not how the deck absorbs the stain and on others where it does. Appreciate any advice! Thank you!!

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Scott Paul ~ Restoring Wood & Decks Since 1993

Reply to Benny

You should never use wood filler on a deck when using a semi-transparent stain, it will not blend. You will need to remove 100% of it or it will show through. Pain as you already know.

We would sand it all evenly with 60 and then 80 grit. We would then let it sit for 1-2 months to acclimate. The final prep would be a wood cleaner and a wood brightener followed by your stain.