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I was wondering if anyone knows a product i can spray on the logs to to make the mold go away. I tried bleach in a small section but the stain went with it.


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Dave - 

Sodium percarbonate cleaners (oxygenated bleach) are pretty mild. We make one called CPR.  There are others out there, found mostly in the laundry detergent aisle at your local grocery store.  (OxyClean is a popular brand has additional surfectants that help with laundry, but has the same active ingredient.)  Those kinds of cleaners do a good job of killing the mold without doing damage to the stain underneath or the wood, so long as the stain is in good shape.  If the stain is in any way compromised, there's not going to be any chemicals that are gentle enough to keep all of your stain intact.  I doubt it will remove all of your stain, but you very well may end up with some blotchy areas in areas where the stain isn't adhering like it did when first applied.  If the stain comes out blotchy at all, it's obviously time for for a maintenance coat of stain or clear coat, depending on what product you used (after you do some more prep to help even out any severe blotchy areas, if there are any).  When you do re-apply the stain, add in an mildewcide.  We like a product called Stay Clean I/E.  M-1 is another brand out there.  They are simply squirted into your stain, mixed in and are applied w/ the stain.  They help control surface mold and mildew growth.

No matter what cleaner you use, you MUST thoroughly rinse!!

Hope that helps some. 

-- Charis w/ Sashco - -

Thanks , I'll give it a try

Use Clorox, it works. 

You can try Lovitt's Wood Cleaner/brightener, you can look at that product at it can be diluted down to do all types of cleaning jobs on and around a log home.

Please DON't use Clorox... the chlorine portion of the bleach is hard on the wood. Oxygenated bleach lacks the chlorine and is must better.


BTW: the reason the black stuff (artilliary fungus) can grow on your wood is because the wood is staying wet enough to support fungal growth. Time to address the finish.



The finish was put on correctly 2 yrs ago and I sprayed water on it this week end and it beeds up like a waxed car.

I agree, don't use any bleach, along with the reasons Wayne pointed out, it also leaves the wood an unnatural color as well as damage the wood.  Here in Washington State, we have seen mold grow on anything and everything literally overnight, it depends on environmental conditions.

You need to determine if the mold is in fact on the surface of the wood finish, or has it grown underneath or "in" the finish.  That will determine your remedy...

Hi Dave,

I just read that you had stained your home 2 years ago and that when you get your logs wet the water beads away. This makes me think that what you really need to do is contact the manufacturer of your finish. They should be able to tell you how to address mold groing on the surface of their product. There are some excellant suggestions on this page but the maufacturer of your finish should be the one that you are talking to in my humble opinion (as an employee of a finish maufacturer).

Good luck,

Kevin, PCS Redmond

When black molds hit my logs I followed what my friend told me and got a positive result. I damped the area with water and scrubbed it with borax. I didn't stop until I saw the the log free from black molds. I let it dry completely with an air dryer and I placed isopropyl alcohol to the area and let it dry. I have been told that moisture is the main cause of molds so after that I made sure that no part of the log will be exposed to moisture. It's a huge help if the storage has proper ventilation and things against moisture. L.R.

Interesting that you bring up black mold.  Just as of last year, 2012 Black Mold is on every single log home we look at in Colorado.  I've been contemplating not so much how to get rid of it, as that is easy, blasting, sanding, pressure washing will easily make it go away, but where is the black mold coming from?  My best guess is all of the dying trees from the pine beetles, billions of trees in Colorado, are rotting and releasing tons of spores.  I can't come up with any other conclusion as the Pine Beetle problem seems to be at epidemic proportions and so is the black mold.  Correlation?  I'm mainly noticing black mold on the exteriors, but also a significant amount on interiors of log homes which can be dangerous to health.  I'm also wondering for those of us in the blasting business what additional mitigation procedures might be necessary if the mold problems get worse?

Hi Dave,

I just wanted to explain to you a little bit about THE FOUR BASIC TYPES OF CLEANERS.

Chlorine Bleach, Oxalic Acid, Sodium Percarbonate Bleach (Oxygen Bleach,) Trisodium Phosphate

Their Respective Pros and Cons
Chlorine Bleach
PROS: Strongly bleaches all types of wood.
Readily available
Kills Mildew
CONS: Chlorine gas can be hazardous or fatal
Readily kills plants, especially new growth.

Oxalic Acid
PROS: Particulary good at removing tannin stains
It is the product of choice on redwood only.
It is the best product for removing rust stains.
CONS: Does not kill mildew
It must be thoroughly rinsed for wood that will be finished with water-based coatings or unsightly whitish blemishes may appear beneath the coating (or other negative effects can occur.)

Sodium Percabonate Bleach (Oxgen Bleach)
PROS: The most environmentally friendly bleach/cleaner
The safest bleach/cleaner
If disassociates into hydrogen peroxide, soda as and water - that's all
CONS: Must not be used on un-aged redwood (it turns it almost black in color)
More expensive than other cleaners/bleaches.

Trisodium Phosphate
PROS: Readily available and cheap
Good for cleaning dirt.
CONS: No bleaching action
Phosphate residues stimulate surface mold growth (it is important tothoroughly rinse.)

I hope this will help you!

Hi Kelly,

We have a general maintenance and pre-finish cleaner called Log Wash that we feel is a very useful tool. It's called Log Wash. Log Wash is a concentrated solution that you mix with water. As opposed to bleach and other solutions, Log Wash does not upset the natural pH balance of the wood, thus preventing wood fiber damage and iron tannate stains. Log Wash will not soften finishes but it will help remove pollen, dust, surface mold, mildew, and pollutants.


As with any cleaner or chemical it is important to adequately rinse after using it. We also recommend using pH Strips to make sure that the surface of the wood has been sufficiently rinsed, preferably to a pH of between 6.5 and 7.5. pH Strips are available at most pool supply dealers, aquarium supply shops and at many Log Home supply stores including Perma-Chink Systems stores. For more information on Log Wash or cleaning wood in general shoot me an email on here or at Or just visit this link LOG WASH.

-Kevin, PCS Redmond


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