# Moldy Redwood Picnic Tables Fix



## katilicous (Oct 26, 2011)

I built 8 picnic tables for my HOA where I live and think I messed up on putting some penetration oil on them too soon after putting on some Thompsons Waterseal if I was supposed to put it on at all. It's pretty damp at night where they sit and they get a fair amount of moisture from the sprinkler mist and sea winds. The tables are 6 months old and I don't want to leave them on their current course bc they are looking pretty blackened. 
Does anyone have a suggestion on how to clean the mold up and protect them without using a clear coat. I know greyin is to be expected but this is like a molding and I don't think it's nice to have.
Should I sand them down and then put something else on them?
Thanks for any help.


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## katilicous (Oct 26, 2011)




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## Unknowncraftsman (Jun 23, 2013)

I doubt there anything you can do.Should have left them natural Thompson water will do nothing but separate you from your money. Wood doesn't need protection for the elements it's a tree trees grow outdoors.
Now sometimes wood needs protection from humans.Esp beer drinking ruffians.Banging beer mugs down on the poor table. Sorry for not helping


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## katilicous (Oct 26, 2011)

How do you mean it will separate u from ur money? Please 'splain thanks.


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## playingwithmywood (Jan 10, 2014)

I would think you could sand to bare wood and then reseal


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## BurlyBob (Mar 13, 2012)

I'm thinking bleach and sanding.


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## playingwithmywood (Jan 10, 2014)

> I m thinking bleach and sanding.
> 
> - BurlyBob


bleaching is probably a good idea also


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## katilicous (Oct 26, 2011)

So then, that's what that wood bleach is for or should I use a liquid Clorox? Is that OK on a picnic table? We don't have many kids here but we got lots of pets.


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## katilicous (Oct 26, 2011)

Thanks, appreciate the wisdom always


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## dhazelton (Feb 11, 2012)

You can use regular clorox and maybe some dish soap with a stiff brush, but were clothes you don't care about and the fumes might be nasty. If you have a small pressure washer you can use a mold and mildew killer for fences and decks, that doesn't smell as bad.

I would suggest that your penetrating oil just sat on top. Thompsons is basically mineral spirits and paraffin. The tables also need to sit where they can dry out after a rain.


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## BillWhite (Jul 23, 2007)

Use oxalic acid. Readily available. Spray it on, wait a while, rinse with a soapy solution to neutralize, brush, rinse, dry, forget any top coat 'cause it'll just go bad in a short time.
Bill


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## tomsteve (Jan 23, 2015)

BE CAREFUL WITH CHLORINE BLEACH ON WOOD
yup, kills the mold and algea great.
HOWEVER
bleach breaks down wood fibers and corrodes metal fasteners. it is next to impossible to completely rinse bleach off of wood as it gets into the fibers. the bleach dries, then when rewetted it reactivates chewing away at the wood fibers again.

look into using sodium percarbonate.


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## tomsteve (Jan 23, 2015)

> Use oxalic acid. Readily available. Spray it on, wait a while, rinse with a soapy solution to neutralize, brush, rinse, dry, forget any top coat cause it ll just go bad in a short time.
> Bill
> 
> - Bill White


or this


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## Yonak (Mar 27, 2014)

Probably the best thing you can do is to get them out of the moisture and let them dry out real good before you refinish them. A good paint and covering when not in use is probably still the best protection against the elements.


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## conifur (Apr 1, 2015)

@Aj2> Wood doesn't need protection for the elements it's a tree trees grow outdoors.
Words of wisdom? but a tree has bark on it!!!


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## Unknowncraftsman (Jun 23, 2013)

Ha Conifer,The bark is to protect the tree from humans.
Bleach oh boy I give up.Carry on without me.


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## conifur (Apr 1, 2015)

@Aj2 >protection ''for'' the elements; ''Ha'' Conifer, learn how to spell then, you might/maybe taken seriously!!!
it is, from the elements and Hey Conifer.


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## kelvancra (May 4, 2010)

That's the same a friend, who owned and operated cedar mills for forty years, said when I told him he needed to get oil into his cedar roof, or it would go south. It was already showing the effects of having gotten wet and drying over the years. The shrinking produced all manner of cracks and, of course, it was brittle in the summer, even in the Northwet (around Ocean Shores, Wash.). He called me back a few years later and asked what he needed to do, because it was looking more like he'd have to pull it and replace it.

Had he saturated the shakes with shingle oil, thinned motor oil or mineral oil, they would have lasted years longer. Too, you could have walked on them in the dead of summer, because they'd remain resilient.



> Wood doesn t need protection for the elements it s a tree trees grow outdoors.
> 
> - Aj2


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## JBrow (Nov 18, 2015)

katilicous,

As others have suggested, you could try bleach (Chlorox or oxalic acid); but before using any chemical, test it out on a piece of scrap or on a small area on the underside of the table. If the redwood retains its color, the chemical should be safe. Chlorox bleach is a 6% solution of sodium hypochlorite. Super Shock carried by pool suppliers is a 9% solution of sodium hypochlorite, and hence a stronger oxidizer.

However, I doubt you will enjoy much success with bleach. My annual ritual is to scrub (using soap and water, a Scotch-Brite pad and a nylon brush) the red oak fence I installed in the back yard. I have found sanding is the only reliable way to remove mold from wood. I have no idea why, because bleach is extremely effective against mold - unless it looks like mold but is something else.

I have not tried pressure washing the fence because I did not want to deal with the fuzz it creates. Nonetheless, I suspect pressure washing would return the wood to its original color and remove most of the discoloration.

Wood kept outdoors requires annual maintenance if a clear coat is applied. The sun will break down whatever coating you apply. This brings me back to my annual ritual with the red oak fence. For about five years I applied a single coat of Sikkens SRD annually, an outdoor protective coating designed to penetrate and protect wood, like decks. It was easy to apply and only required washing before re-coating (and in my case, spot sanding). However, Sikkens SRD did not last even a whole summer in the mid-west, breaking down in various locations on the fence. However, it did a great job of preserving the red oak and its original color.

PPG, the label's owner, recommended I switch to Sikkens Cetrol 1 RE, which I did last spring. Two coats are required initially and the recoated as needed. I think it is a penetrating product used a base coat for their other products, but useful by itself in my application. So far, this product seems to be holding up well; and better than Sikkens SRD.

Twin Creeks Log Homes in Tennessee at 423-477-3107 is where I bought the Sikkens product and they seem knowledgeable regarding outdoor finishes.


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## Unknowncraftsman (Jun 23, 2013)

Cedar shingles don't need any treatment,They do shrink and dry out in the summer it give the attic a natural ventilation.When it rains they swell up tighter than a frogs ass.
I've done lots of shingles and shakes roof restoration and was a roofer for 35 years.Thats way I have crazy hand tool skills.
But as conifur has pointed out i am not much of a word worker. 
Rather be a woodworker than wordworker. Carry on…...


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## katilicous (Oct 26, 2011)

Wow, a topic with some great responses and a lot of options it would appear…
The tables dry out during the day, most days, but hearing that bleach will have a degenerative effect is enough for me to stay clear of it. I might try a light pressure wash then a light sand and then after that realize I prob need a heavy pressure wash and heavy sand to start fresh. The color is pretty nice without the mold and I don't want that to go away with bleach. 
Is Sikkens like the General Finishes of a Thompsons kind of product? I didnt quote a finish into the bid for the tables but I don't like them representing me how they stand now so before Spring I want to do something.
Thanks for all the wisdom.


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## JBrow (Nov 18, 2015)

katilicous,

I do not understand your question - but I'll try to answer anyway. Sikkens is a wood protective coating. It absorbs UV light and restrains the penetration of water and air. I have not used Thompson Water Sealer so I cannot offer an opinion regarding this product.

My experience with Sikkens SDR is that it is very effective in protecting the wood, but begins to fail within a year on red oak. There has been very little checking in the red oak fence. Also, except in the various scattered areas where the protective coat wore away, the color of the red oak has not changed in the 5 years the product has been used (re-applied annually).

Sikkens SDR is applied with a brush to a clean surface. It is oil based and has quite an odor, so ventilation is required. I have had to clean red oak fence and reapply the Sikkens SDR annually, but that is consistent with the manufacturer's product claim - hardwoods require more frequent maintenance. The finish is not a film finish, so when the finish breaks down, no sanding or other preparation is required before reapplication. It is a one coat product.

The Sikkens SDR may perform better on redwood than on hardwoods. The Sikkens SDR lasted 3 years without any issues on our pressure treated pine privacy fence. When it was reapplied, the only recommended prep work was washing the fence, which I did not do. It was rolled on and back brushed per manufacturer instruction. The privacy fence darkened a good bit after the maintenance application; probably because I was too lazy to pressure wash the fence.

The photo is intended to show how the product performs. It shows the red oak fence and the privacy fence, taken a few weeks ago. I hope it helps you a little.

I think some of Sikkens products are carried by the Home Depot, including Sikkens SDR. I am not sure about the cost, but I am pretty sure it is less than $50 per gallon. A gallon might cover 5 picnic tables, but since it is raw wood, I am not sure.

The Sikkens Cetol I RE is a base coat for their other products, but goes on like the Sikkens SDR. However, two coats were recommended for the red oak fence. The company thinks this product will perform better for me on the red oak, so I switched to it on the red oak. The jury is still out - but it looks good so far. I think it is a penetrating "primer" coat, but I am not sure. In my case, it was an initial two coat application - suggesting it as the properties of a film finish. I expect to apply only one coat for maintenance.

My recommendation is that if you are seriously considering the Sikkens product for the picnic tables, call Twin Creeks Log Homes. They seem very knowledgeable in outdoor finishes and may save you money and aggravation.


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## MNgary (Oct 13, 2011)

I use hydrogen peroxide to kill mold - the stuff you can buy at your drugstore. I spray a heavy coat on, wait a day or two and spray on another coat. Just leave the heavy coats alone, they will dry and not damage the wood. The black disappears as the mold dies, which usually happens within a day or three.


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