Bed Wood Problem

[Shaun1162]

So, I have a problem with the bed wood I just finished for my flatbed. I used red oak, and used a 50/50 mix of linseed oil and turpentine, after several recommended it. I coated all 4 sides, as well as the ends, plus coated the holes that we drilled for the bolts (all stainless steel).

The wood received three coats of the 50/50 mix before we put it on. It's been indoors drying for about a week now. Today, I backed the truck out to wash it. I got some water on the wood, but didn't think much of it until I was walking by later and saw a bunch of black spots all over the wood. It almost looks like a black mold on it? There's more stains around the bolt heads, but theres still spots throughout now.

Anyone have an idea what the stains are from? The stainless steel bolts? Or how I can maybe get them out, or prevent it from happening again?

Any help is appreciated... Really discouraged from it

[AusTx68]

The way I understand it, a linseed finish is easily penetrated by water. Usually occurs within minutes. If the water makes it down to the wood it causes dark spots that can only be fixed by stripping the wood. I'm not speaking by experience. I found that thru Google. With that said, what's the benefit of using linseed oil if it doesn't act as a barrier to water??

[Shaun1162]

Originally Posted by AusTx68

The way I understand it, a linseed finish is easily penetrated by water. Usually occurs within minutes. If the water makes it down to the wood it causes dark spots that can only be fixed by stripping the wood. I'm not speaking by experience. I found that thru Google. With that said, what's the benefit of using linseed oil if it doesn't act as a barrier to water??

I know little about woodwork (more of an autobody man), so I went by what a few old carpenters told me. The first told me to use the 50/50 mix, and 2 or 3 others told that would work fine.... I tried using some stripper and it didn't help much..

[slomotion]

It could be a mold, linseed oil is an organic material. Can you physically scrape them away, or is it imbedded in the wood? Did you by any chance use steel wool on the decking? If so, it could be rust spots.
Can you take a picture of it and post it?
Something you might try is make up a bucket of mild bleach solution and wipe it down with that to see if any of the black spots come off. If they come off easily whatever it is is on the surface, not in the oak. Linseed and turps is a good penetrant, but I don't know if I'd rely on just that for a finish. If your truck will be out in the sun alot, the finish you have on it may feel tacky on a hot day.

[Steve Hafner]

. . . .

I just finished my Red Oak a few months ago.

It has two coats of dark walnut stain to bring the grain out followed by five coats of semi-gloss marine spar varnish with UV protection.

The first coat was 90% varnish - 10% lacquer thinner.

The second and third coats were 75% varnish.

The fourth and fifth coats were 100% varnish.

I was very happy with how it turned out ( considering "I" did the work !!! )

. . . .

[Richard H.]

As Slowmotion suggested use bleach , it will lighten the wood so you will need to stain it liberally.

[Shaun1162]

I will definately take everyone's advice... I lightly hand sanded parts today with 320 grit and that got most of the black out, so thankfully it's on the surface.

Steve, your the finish on your bed looks great... I'll try to get some spar finish. I'm sure a marine grade would hold up well... My truck will probably stay outside all summer so it'll probably need the extra protection.

Thanks for the help guys!

['68 C-20]

Oak is high in Tannic Acid. When it makes contact with iron and oxygen, it turns dark blue to black. Could it be that you had some metal shavings or filings that got left on the wood and sealed under the Linseed oil?

[Shaun1162]

Well, went with some marine grade Spar varnish. Went on really well over the linseed (sanded the black spots out first), and seems to be much more durable.

Bed wood looks much better now! Thanks again guys

[Steve Hafner]

. . . .

After my wood dried for about a month, I put on a couple coats of this wax from: www.daklabs.com that's made for wood boats.

I was told that this step would help the finish hold up even better.

. . . .