"AAARRRRGGGGHHHH! Mold on laser cut mdf!" Topic

I have a bunch of less than 6 months old laser cut mdf.
Sarissa, mainly.
I assembled about 4, and gave some a preliminary base coat of Krylon Camouflage Dark Brown.
I stored them in a Sterilite 3 drawer wheeled chest. It stands in my basement.

I was just looking at them, and after less than 3 weeks, most are covered in a fine powdery gray mold. Both bare mdf and painted surfaces.
This did not happen with any plastic or resin buildings. Just the laser cut mdf.

A few laser cut mdf buildings that were never put away are still pristine. They were in the basement too, just not under cover.

So why were only the laser cut mdf in storage not affected? Not the resin or plastic?
What can I do to clean them off and make sure it doesn't happen again?

I'd definitely bleach out the storage chest. Sounds like there was the perfect storm of humidity, enclosed space & darkness for the mold to grow on the mdf (probably came in on it.) For the moldy stuff, bleach & brush (outside), dry, repaint. If you have nice, strong UV lamps, I'd bathe everything in the light to kill off mold spores…

MDF board is composed of essentially many layers of compressed paper and pulped wood fiber derivatives. So MDF can mold the same way as when you store paperwork in humid conditions. Your basement is obviously humid (I assume it's a part of the house where air conditioning doesn't reach), that combined with putting them in drawers that were plastic which kept the moisture sealed in with the MDF pieces.

Made for ideal conditions for mold to grow, as Zephyr1 said.

If it's possible I would invest in a de-humidifier for the basement and keep the MDF on open shelves, not in closed drawers. Dehumidifiers are amazing. We have one in the basement and we're able to store clothing, including woolens without any mold issues. During the summer we have to empty the water out of it about every two days. It's incredible how much water it pulls out of the air.

Other option is to make space somewhere upstairs to store your MDF where it's less humid.

Thanks, from a sadder but wiser man.

Serves you right for not scratchbuilding.

Something I've started doing is putting moisture absorbing sachets in my KR multicases (which are card cases, storing figures based on MDF). Didn't have problems, but figured it couldn't hurt and might prevent future problems like this.

When I get stuff from the store that comes with those desiccant packets, my family knows to deposit them on my painting table. I usually throw one or two in all of my figure and terrain storage boxes.

Thank you for this advice. Sorry for your buildings, hope you can fix them.

Yeah, the good news is that if you bring the MDF upstairs and put it in a dry, well-lit place it should kill off the mold and then you can dust it off the pieces. Once they're dry and cleaned off you should be able to do a spray coat over it again or a coat of brush-on paint.

Sorry for this happening to you, but thanks a lot for the advice of taking care with humidity and MDF buildings.

I'm planning on scrubbing them down with Clorox bleach and a toothbrush.
I guess that'll ruin any paint job, but so far just a base coat of dark brown.

I did want them to have a weathered look but this is ridiculous.

+1 Markconz.

I had a friend many years ago who went on deployment. While he was gone, his wife stored about 40 Avalon Hill, Yaquinto, SPI, GDW and other wargames in the AC closet. When he came back, they were all just so much moss.

Sob.

Spot test. I'm storing them in the same bin, but out in the open air on top of a table.
I put a Tupperware basin in it with an inch of Clorox bleach in it.
A preliminary scrub of a patch seems to clean it fine. Now to see if the bleach affects the paint job.
Anyway, I'm getting some particle masks. Already have blue Nitrile gloves.

If it's a porous material like mdf, bleach can only help for a short while.

A light and very diluted misting of this (read instructions on back), or your local equivalent, should take care of your problem for several years. It kills the fungus and prevents all new growth.

And, after it dries thoroughly, make sure to spray everything down one last time with a matte polyurethane sealer.

Dan
PS. If your storage area is that damp, you should consider putting a small bag of desiccant in each bin. At the very least.

I was thinking that had I put them together in the winter, with the furnace blasting and low humidity, I would not have had a problem. Until next June…
Glup

Anti-mold compound, mix 1/4 teaspoon of oil of cloves in a litre of water in a spay bottle, mist. let dry and wipe down.

David F Brown

Will certainly smell nice.

Well, spray bleach certainly killed the mold. Now I'm stuck with tenacious fibers that have to be scrubbed off.
Stuff toothbrush I guess. With gloves and a mask.

Must you really scrub them? How bad does it look now, after the bleach? I'm really curious. Got pics?

Dan
PS. I would rather you paint, or flock, or spray seal them in some other way, than risk scrubbing them into breathable particles.

You are painting wood. Can you get Zinsser Mold Killing Primer? link It's a Rustoleum product and is available in big box stores. Sounds like you might want to use it as your regular primer going forward.

If you're going to brush on that first coat, there's a similar additive that can be put into your paints. I know I've seen it at Sherwin Williams.

Dan

I'm thinking of a nice 1:56 bonfire…

See post number 5.

I am so sorry. It must be so frustrating.

Dan

Chucked them all out behind the garage.
My wasted time is what annoys me the most.
It's the big Russian house from Sarissa or Charlie Foxtrot that looks like a barn, and the windmill from Thingsfromthebasement.

Stuff stored in my basement in the open are unaffected. Ditto resin and plastic models in the same bin!
Interestingly enough, a roof that I thought had too much paint on both sides might have come through. If not, there's always foam core.

I learned a lesson. I hope I helped others.

MDF is basically cheap paper. Any moisture and it becomes a problem. I dislike it intensely. I worked my way through college as a carpenter and I prefer to work with real woods, preferably hardwoods. Just a personal prejudice.

I thought I'd be helpful and revive this thread from 6 years ago as there is a mention of this problem in this months UK Wargames magazine. I wish I had be aware of this. I had to throw out a lot of laser mdf I had bought and figure storage boxes I had made. I did try cleaning it with a mould spray but it just grew back :(

It's been very damp here in the UK and to make matters worse my collection is stored down my cellar/ basement. I know mates who have their stuff in sheds!!

So I'm going to avoid MDF in the future.