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Blotchiness after pressure washing

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(@pd512)
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Joined: 7 months ago
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Hi,

We have a deck that is 7 years old. Yesterday for the first time ever, I decided to clean it with a pressure washer. Next I plan to seal it before the winter. I live in Canada and our winters are long and we get a lot of snow.

I read other posts on this forum and although it's a bit hard to tell from the other users' photos, if I had to diagnose it I think I pressure-washed too harshly. First-timer here. I think I went too close and didn't feather out.

Part of the deck has become blotchy, i.e. there's the original greyish areas, and now some areas that are yellow.

I've uploaded the photos to my Google Photos account (I keep getting an error when I try to attach photos to this forum post). Photos:

Do I now need to sand it? It's not a large area...only 8' x 5' so I could do it with a handheld sander.

What if I don't sand it and just go ahead and seal it? Will the colours level out on their own over time with oxidation?

Thank you for creating this great website and community, which is such a valuable resource.


   
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Scott Paul ~ Restoring Wood & Decks Since 1993
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Joined: 13 years ago
Posts: 3326
 

Posted by: @pd512

Hi,

We have a deck that is 7 years old. Yesterday for the first time ever, I decided to clean it with a pressure washer. Next I plan to seal it before the winter. I live in Canada and our winters are long and we get a lot of snow.

I read other posts on this forum and although it's a bit hard to tell from the other users' photos, if I had to diagnose it I think I pressure-washed too harshly. First-timer here. I think I went too close and didn't feather out.

Part of the deck has become blotchy, i.e. there's the original greyish areas, and now some areas that are yellow.

I've uploaded the photos to my Google Photos account (I keep getting an error when I try to attach photos to this forum post). Photos:

Do I now need to sand it? It's not a large area...only 8' x 5' so I could do it with a handheld sander.

What if I don't sand it and just go ahead and seal it? Will the colours level out on their own over time with oxidation?

Thank you for creating this great website and community, which is such a valuable resource.

You did not fully remove all the gray oxidation. You could go over it one more time with cleaning if you like, or you could sand it all. Staining it as it looks now should work, but you will have some color variation when it dries.

 


   
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(@pd512)
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Joined: 7 months ago
Posts: 3
Topic starter  

Thank you Scott.

Just to clarify, we're actually going to be sealing it, not staining it. Not sure if that makes a difference in regards to the advice.


   
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Scott Paul ~ Restoring Wood & Decks Since 1993
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Joined: 13 years ago
Posts: 3326

   
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(@pd512)
Active Member
Joined: 7 months ago
Posts: 3
Topic starter  

The sealer is a semi-transparent with a moderate colour in it. It's. The company advertises that it provides durable protection from sun damage.

Also, I didn't use a cleaner/brightener when I pressure washed....only water, followed by a round of scrubbing with a strong broom. Since then I've read some of your posts where you suggest using a cleaner/brightener. But if I go over it again with only water to remove the gray, then do a bit of a sanding and then apply the semi-transparent sealer, would that be sufficient?


   
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Scott Paul ~ Restoring Wood & Decks Since 1993
(@administrator)
Member Admin
Joined: 13 years ago
Posts: 3326
 

Posted by: @pd512

The sealer is a semi-transparent with a moderate colour in it. It's. The company advertises that it provides durable protection from sun damage.

Also, I didn't use a cleaner/brightener when I pressure washed....only water, followed by a round of scrubbing with a strong broom. Since then I've read some of your posts where you suggest using a cleaner/brightener. But if I go over it again with only water to remove the gray, then do a bit of a sanding and then apply the semi-transparent sealer, would that be sufficient?

That means it is a stain, not a sealer. Sealers are clear. If it has color in it, then it is considered a stain. You should use a deck cleaner, and then light pressure wash off. Brightener last. You probably do not need to sand it.

 


   
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