# Understanding Deck Stains and Sealers



## joewho (Nov 1, 2006)

Good post.

What about products that advertise a "sunscreen"? 

What about oil based stains vs. water stains as far as mold? 

Figured as long as you're being generous with info, I'd ask.

thanks


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## RAD Systems (Nov 15, 2006)

Not a problem, Joe, I'd be happy to answer your questions.

Just like a sunscreen for your skin, a product can offer a deck's surface UV protection from drying out and looking old and gray. The only way for a stain to do what is through pigmentation. The more it has, the better your protection. Of course the more pigmentation a stain has the more it may end up looking very dark or like paint. Its a balancing act. The more "natural" you want your wood to look the more often you are going to have to clean and seal your deck. Clear sealers = no protection.

A quality oil based stain/sealer is always going to be superior. It acts as an emollient for the wood, conditioning it and slowing moisture penetration. The reason I use the word quality is because in order for an oil based stain to last in an exterior enviroment it has to have decent levels of mildewcide. Many of the large big box store products do not contain adequate mildewcide. Thats why I recommend DIY'ers to avoid them like the plague (among other reasons as well)


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## joewho (Nov 1, 2006)

Thanks for that information.

Couple more questions, if you don't mind. 

Does bleaching your deck work as well as a deck cleaner?

Does mildewcide effect pigmented or solids differently than clear oil products?


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## RAD Systems (Nov 15, 2006)

You will find the consensus among professionals split on the use of bleach on wooden decks. Most think its a bad idea. There are still some guys that swear by it. In my opinion, on untreated wood it is not a good idea. It tends to rob the woods natural protective oils. I can always tell a deck that been treated consistently with bleach (sodium hypochlorite) based cleaners. Sodium hypochlorite leaves the wood an unnatural white/silver and usually means you have to use 20% more stain/sealer to replace what is removed. A year ago I saw an electron microscopic scan of two pieces of wood. They were both from the same tre and lot so the variables of species, climate etc were removed. Each of these pieces were cleaned with differing methods. The one cleaned with bleach showed wood fibers in a jumbled mess. Something happened molecularly to the wood. It changed and absorption at the surface (where you get your protection) was affected negatively. 

Now on the other hand, if your wood is painted or has intact sealer on the surface (it still repels water) its okay to use a little bleach and a mild detergent like dish soap to clean off surface growth. Keep in mind that bleach is not a cleaner, so it needs some soap aded to it. The wrong kind of soap or too much and you have a rinsing nightmare. Its really best to use an oxygen based wood cleaner and then to pH balance the wood to set it up for sealer. 

The majority of deck cleaners you buy in Home Depot or Lowe's are overpriced mixes of bleach and soap. If you are going to go that route, make your own by mixing stroe bleach 50/50 with water and maybe one squeeze of Dawn. Again, I don't recomend you use bleach on untreated wood for the reasons above.

Joe, on the last question. I would venture to say no. I am not a stain manufacturer though I do know a bit about the chemistry. From a user standpoint there is no discernible difference. I'll speak with a coatings chemist and get back to you if I find out differently.


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## joewho (Nov 1, 2006)

Ken,

I sent an e-mail to you at your site. Your name in the subject line.


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## RAD Systems (Nov 15, 2006)

Joe, thank you for the compliments and I did recieve your email.


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