Black Mould on Birch Ply - advice needed

[mikej460]

Over the last few months I've made several workshop items using birch ply which I varnished with 3 coats of Ronseal (router table, bench sander and sanding organiser). I've left them in the garage, together with all the offcuts and the amount of rain we've had has made the garage very damp and all the birch ply, even the varnished items, are covered in black mould! The unvarnished offcuts are worse but can anybody advise how I can treat this please? and can I totally remove the black staining?

 

[Sideways]

Proprietary mould spray works on hard surfaces, vinyl wallpaper and the like. It's a strong alkali with some bleach. I might try it if nothing else is suggested. Wear gloves or a strong one will dissolve your fingerprints off !

 

[TheTiddles]

Wow, I can only assume you had some mould on it before varnishing, my ply suffers the same, but that which is finished doesn’t

 

[Jameshow]

Is it sugars in birch that makes it mould prone and rot quickly??

 

[baldkev]

I would be tempted to try oxalic acid, but of course you wont want too much moisture on there. Peroxide is possibly an option, its used as 'wood bleach' in a lot of the kits. You can get 9% hydrogen peroxide from boots etc.

 

[baldkev]

Just to add, i guess test on the offcuts first

 

[mikej460]

Is it sugars in birch that makes it mould prone and rot quickly??

Yes I think you're right as none of the standard ply has been affected. This has happened over the last week.

 

[eribaMotters]

Avoid expensive treatments and resort to bleach. Wipe on a 1 part bleach to 4 parts water mix. Leave for 24 hrs and repeat. Wipe surface clean with a damp water rag after another 24 hrs and leave to dry. You will then need to give a light sand as the grain will have swollen and raised.
This method is also good for killing mould on painted surfaces prior to repainting.

Colin

 

[mikej460]

Wow, I can only assume you had some mould on it before varnishing, my ply suffers the same, but that which is finished doesn’t

Yes the untreated is far worse but the router table (3 coats of shellac sanding sealer) is bad and the other two that have been varnished are not as bad but enough to worry me.

 

[mikej460]

Avoid expensive treatments and resort to bleach. Wipe on a 1 part bleach to 4 parts water mix. Leave for 24 hrs and repeat. Wipe surface clean with a damp water rag after another 24 hrs and leave to dry. You will then need to give a light sand as the grain will have swollen and raised.
This method is also good for killing mould on painted surfaces prior to repainting.

Colin

As I had it in, I have sprayed this onto the bench sander and sanding station and wiped with a sponge pad Zep Mould & Mildew Stain Remover 750ml | Mould Remover | Screwfix.com. If it looks any better tomorrow I'll treat the router table with it. If not I'll try the bleach solution.

 

[baldkev]

Avoid expensive treatments and resort to bleach. Wipe on a 1 part bleach to 4 parts water mix. Leave for 24 hrs and repeat. Wipe surface clean with a damp water rag after another 24 hrs and leave to dry. You will then need to give a light sand as the grain will have swollen and raised.
This method is also good for killing mould on painted surfaces prior to repainting.

Colin

Hi colin, i believe where mould is concerned, normal bleach can often make it worse in the long run.... i believe it comes back blacker each time.... apparently theres a couple of types of bacteria in mould and household bleach kills the wrong ones, so specific mould killer and fungicide are apparently more effective.

 

[mccpe]

I’ve used bleach in the past, the cheapest bleach from Tesco. I don’t think that you can prevent it from returning, whatever you use (been there, done that), you either have to change the conditions that you keep the birch in to prevent fungus returning, or you need to paint it.

 

[eribaMotters]

A second application is needed as some spores resist the original application.

Colin

 

[hairy]

Black mould is a common thing on older, left for a while, insufficiently ventilated campers. The advice there is often bin the insides, for health rather than appearance sake. I've read that the "roots" of black mould go deeper in than bleach will reach, so you may make what's there invisible but not kill it.
We have two little recurring spots in our bathroom which bleach has not resolved. Next to try is some borax which someone somewhere said was good allegedly.
I'd be interested how you get on,.