Hi all. I recently built a deck out of pressure treated lumber. Now comes the time for the staining of it and I get all kinds of advice …many many conflicting ones.

I read that on new PT wood it is necessary to first wash the deck with those products called “deck wash” and or “deck cleaners”. And the reasoning apparently behind this is to, and I quote here, “remove the mill finish”  on the lumber because this apparently  will allow the forthcoming stain to penetrate more readily.

Really? Or is this just marketing speak? Is there a basis for this? My reasoning says there isn’t and this is just a way to get you to buy another unnecessary product. My reasoning is this…

I occasionally build furniture and have found that after milling my lumber on tablesaws, planers, jointers, etc the wood readily takes stain without me having to wash it with a cleaner to remove the factory mill finish. In this case I’ve put the factory mill finish on the lumber with my machines. So why do I need a deck wash/cleaner?

Now, yes, I understand that maybe with my deck I’ve tracked dirt on to the lumber and that needs to be cleaned off but my question goes to the “mill finish removal” argument.

So what do you think? Are deck wash and deck cleaners on new PT would just hype? Can I just apply the stain after washing the deck with water (and waiting for that to dry of course before applying the stain)?

Also another question that I get all kinds of answers to is, “How long do I wait to apply the stain to the deck?” I get all kinds of answers from 1 month to a whole season to an entire year. My deck gets full sun fro most of the day and with this years hot weather my deck has been baking since about mid June. The boards already have some cracking and cupping occuring and the sun has changed their color to what I would say is a sort of yellowish (initially they were more whitish when first constructed).

I notice when it rains (and that’s been few and far between lately here in southeast PA near Philadelphia) the water gets absorbed by the lumber and does not bead or stay on the surface much. Is it time to stain? I’ll be using an oil-based semi-transparent stain.

Thanks to everyone in advance.