Deck that needs cleaning ONLY - what to use

[Curb Appeal 14]

Hello all,

I have a lady here that I have done a lot of work for and is a great customer. She stains her deck herself every couple of years because she actually enjoys it. She will be going back over it with the same color, semi-transparent stain.

It's time again and she wants me to clean the mold and mildew off so she can stain it. I'm wondering what to use. I need to get the green and black stuff off without stripping the stain.

Suggestions?

[squirtgun 122]

Look everybody a chance to debate percarb~vs~bleach.

Joel,

There are 2 schools of thought on cleaning mildew/mold from decks.Both work and are very effective.Once all of the "woodies" have spoken decide which will work best for your situation and forge ahead.Good Luck!

[Curb Appeal 14]

Yes I've used both on decks before, but that was on untreated decks prior to stain. This time I need to be a little gentler and not damage the stain under the mold and mildew which, by the way is not that heavy at all.

There are just a few bad spots here and there but mostly it's in good shape.

[Deck Guy 14]

Assuming you have at least a 4 GPM machine, go with either mix debated here and a 4010 tip. Keep far enough away from the deck so you do at least one full board per pass, and you'll be okay.

[seymore 90]

Yes I've used both on decks before, but that was on untreated decks prior to stain. This time I need to be a little gentler and not damage the stain under the mold and mildew which, by the way is not that heavy at all.

There are just a few bad spots here and there but mostly it's in good shape.

The stian will lighten up somewhat if you use a bleach mix.It would be the only way to kill mildew in the wood.If you have just surface mildew mix a solution of 10% solution and use a real soft brush like the carwash brushes.I wouldn't use a pressure washer just light scrubb the worst spots and then apply the new stain.

Now if the mildew is on the surface it should be removed real easy.If there are black mildew spots under the stain then removing the old stain to bare wood to treat the mildew with bleach is the only way.

You don't know what was the old stain you are cleaning?

This is how i work on my maintance jobs cleaning a oil base semi trans stain.

[PressurePros 248]

This is a situation where using bleach is a no-brainer as long as the surface does not still repel liquid. If you test it with some water and that water beads on the surface, you need a percarb based cleaner.

[Curb Appeal 14]

This is a situation where using bleach is a no-brainer as long as the surface does not still repel liquid. If you test it with some water and that water beads on the surface, you need a percarb based cleaner.

By bleach are you referring to store bought household bleach? If so, what strength do you recommend I should mix it?

[PressurePros 248]

Joel, I am by no means an expert with bleach. Up here growth isn't bad so I downstream pool shock (12.5 sodium hypochlorite). To get an equivalent mixture, you would mix store bleach 50/50 with water. Some other guys will help you out with various mixtures whom have more experience with it on wood. I am more of a sodium percarbonate person when it comes to prepping for sealer.

[Curb Appeal 14]

In the past, I too have liked the percarb cleaners better. So do my customers. Steve Rowlett has a house wash mix (RPC143) that he recommended to me and I think I'll try that. Plus he's right down the street.

Thanks for the suggesttions...