Spotty Doors

[GroundFig]

We have a few pine doors upstairs in our cottage. I originally thought they were unfinished but now think they are probably waxed. Over the winter lots of small dark spots have appeared on all the doors and are gradually spreading. I have no idea what this is (some kind of wax mould?) and wondered if anyone had ever experienced anything like it before. The house has been quite cold over the winter. White spirit, meths and alcohol seem to have little immediate effect.

Any ideas what to do about it?

 

[Racers]

Its probably the stuff that they where dipped in to strip them coming out.

Pete

 

[GroundFig]

That's an interesting thought, any idea what to do about it? I should have mentioned they've been fine for the last five years we've been here and as far as I know they've been as they are now for some time before that, so strange for something to suddenly start this year.

 

[sawdust1]

Are they near to a sink as they look like the wax finish has been splashed with water ?
When the stripping solution bleeds out it usually shows as wet patches not splash marks.
If its either then difficult to remove, apart from sanding and refinishing.

 

[GroundFig]

No, none of the doors are near any kind of water. The marks are on both sides of three different bedroom doors (the bathroom door is a different type).

 

[Woody2Shoes]

These doors look like they've been dipped in hot caustic soda (sodium hydroxide) to clean off all the old (lead) paint.

I think that the patches you're seeing are where the stripping solution has not been completely removed/neutralized after the dipping.

Sodium hydroxide is hygroscopic, sucking moisture from the air, giving the darker appearance.

I think that a good way to try and neutralise the residual gack would be to wipe vigourously with domestic vinegar - I have high hopes that this will work, but it's unlikely to do any damage even if it doesn't!

Cheers, W2S

 

[ED65]

White spirit, meths and alcohol seem to have little immediate effect.

Try water.

Go to one of the spots that you've previously wiped with white spirit/alcohol and go over the area with a damp cloth. If the colour of the wetted wood equalises there's a good chance the spots are due to water from the air.

 

[Woody2Shoes]

White spirit, meths and alcohol seem to have little immediate effect.

Probably because they do little/nothing to remove the residue of Sodium Hydroxide. Vinegar will neutralize the alkali and convert it into sodium acetate....

NaOH + CH3COOH -> C2H3NaO2 + etc.

https://www.quora.com/What-is-the-chemi ... oxide-NaOH

 

[GroundFig]

Not had a great deal of success unfortunately. Vinegar has some effect, but also lightens the wood. It seems scrubbing with a scourer and white spirit is the most effective, but still not brilliant. It looks like I'll maybe have to strip the wax off, sand and refinish.

 

[ColeyS1]

What's in the centre of the blobs ?

I'm only looking on my phone but they look like small specks of something, spreading out forming the blotches. What's the other long line that I've circled - Kinda looks like a cobweb ?

Sent from my SM-G900F using Tapatalk

 

[GroundFig]

Not sure what it is. Either something growing from the patches or it might be dust that is for some reason attracted to the patches. There are lots of patches that don't have stuff coming out of them. Not that our house isn't fastidiously clean or anything.

 

[Harbo]

Probably some form of fungicidal attack.
Sand to bare wood, apply fungicide and apply new finish.

Rod

 

[GroundFig]

Yes, I think I'll give that a go. Thanks to all for advice.

 

[screwpainting]

Try using a very hot iron over a sheet of plain white paper, if its organic that should kill it and may even burn out the stain. For some reason this rings a bell... I suppose there's nothing to lose, and it's easy enough to try .

 

[ED65]

Vinegar has some effect, but also lightens the wood.

Yes any water or watery liquid scrubbed into wood will tend to literally clean it as it removes some of the compounds that rise to the surface (called extractives), but rest assured it'll return to the colour you're used to before you know it.

Obviously sanding will soon take it down to the even lighter colour of fresh wood so you'll have to be more patient, it might take a year or so before the wood has settled back to a colour you're happy with on an interior door which doesn't see much sunlight.