Cleaning Kiln Dried White Pine

[Casey 14]

Hi all! We had a request from a customer to clean a kiln dried white pine deck. He said the wood was called "Thermal Guard". I could not find any info about it via Google. He said is is not pressure treated.

 

He wants the wood clean, but also want to preserve the "patina" of the wood. He said the wood had kind of an aged look to it when it was new. He does not want any stain applied after cleaning either.

 

I know we could clean this one and make it look like new wood, but that is not what he is after.

 

Any suggestions on this one?

 

Thanks for any input!

[RPetry 564]

Hi Casey,

A bit difficult to tell the condition of the white pine/"patina" as the wood appears wet in the picture. There does appear to be mold/mildew on the wood under the chairs/roof eave.

Try a small test spot with a sodium hypochlorite (chlorine bleach) solution and a bit of soap. No more than 1 - 1.5% NaClO. Lightly scrub one or two passes with a soft brush and rinse off with no more than spigot hose pressure.

It is the claimed "patina" that would concern me as a contractor.

[Casey 14]

Hi Rick,

 

Thanks for the reply. Yes there is definitely some algae/mold in areas of the deck.

 

If I am doing my math right, would 1 gal of 12% NaClO + 4 Gal of water in a 5 gal bucket = a 1.5% solution of NaClO?

 

I was kind of thinking something along this route since we have successfully cleaned some composite decks in a similar manner. I just did not know if it would be as effective on wood. I guess the 1.5% solution and no pressure would have the best chance of preserving the "patina". The customer has some compost bins built out of the same material so he said we can do all the testing we want on those.

[RPetry 564]

Casey,

 

NO!  Sorry, just got in from estimates.  Think of it this way.  1 gallon of 12% chlorine bleach,  in a bucket.  Add one gallon of water and it is now 6%.  Now you have 2 gallons of chlorine bleach at 6%.  Add  2 gallons of water.  Now you have 4 gallons of chlorine bleach at 3%.

 

Take a breath.  OK, 4 gallons of mix at 3%.  Now add another 4 gallons of water.  Wala!  You now have 8 gallons of proper bleach mix ( 1.5% sodium hypochlorite) for wood!  Add a bit of soap and stir.  Killing mold/mildew on wood is easy, inexpensive, and effective.  After drying, if it still is now up to snuff, you have another problem.  IMO, anything stronger is a waste of chems and possibly bad for the wood.

 

Very light pressure on the wand.

[Casey 14]

Hi Rick,

 

Thanks for clearing that up. Makes sense now.12% divided by 1.5% = 8.         1 gallon of 12% SH to 8 Gal of water.

 

Just out of curiosity, do you have any idea what other problems I may encounter if it does not look right after drying? Just trying to be prepared.

 

We won the bid and will be doing the job the last week of July. I will report back on how it turns out.

[RPetry 564]

Hi Casey,

 

If you want to provide "first class, Rolls Royce" service, additional chems as follows.  Lightly rinse off the chlorine bleach mix, blow off/squeegee excess water.  Apply a sodium percarbonate wood cleaner, mixed at 6 oz./gal. of chem.  Apply to all the wood, and wash with a bit of pressure, you can tell when it is clean just using a dual lance wand.  Follow up with an acid neutralizer/brightener at 5 - 6 oz/gal.  We use citric, oxalic also works.

 

We do not rinse the acid, but, with very few exceptions, only use Ready Seal stain.  Check with the manufacturer of the stain you plan to apply.

 

I'd still test, this claimed "patina" has me stumped.