A few months ago, I was working on building Supertrees for my layout, and I mixed up a mix of matte medium from AC Moore and water to bond the foliage to the tree armature. Just weeks later I tore down the entire layout, put a lid on my matte medium/water mix (it was in a half-gallon reused ice cream container) and stacked it in a corner with the rest of my scenery stuff.
Fast forward to this week, when I was moving stuff to make room for more benchwork construction (eventually everything will be stored underneath the layout) I opened up the container to see what was in it. (it was one of the few containers I neglected to label)
Surprise, surprise, there was a layer of mold or fungus floating on top of the matte medium. I think I’ll be able to overcome the smell long enough to skim off the gunk and be able to reuse the solution underneath when I’m ready to start building trees for my next layout, but if you’re thinking of storing matte medium for a while, be warned!
I somehow don’t think using matte medium that has had mold or fungus growing in it is a good idea. I’d think the whole batch is now contaminated, and if it were used on a future tree project, you’ll have a forest of mold/fungus on your layout.
Go to a wine/beer-making outlet and buy a $0.99 package of a white powder called sodium meta-bisulphite. Sometimes potassium meta-bisulphite. Mix a teaspoon of that powder in your matte medium mixture, thoroughly agitating it to ensure homogeneity, and then use it with impunity. The bisulphite will kill the mold, and bacteria, and the spores.
I’m not a microbiologist (I don’t even play one on T.V.) but I would tend to think that the mold or whatever it was, came from the water you mixed with the matte medium rather than the matte medium itself - especially if it was just tap water.
You are most likely correct. Tap water is considered clean not sterile. You can grow a fascinating array of microorganisms from take waters from different areas. Another factor may be that the mold spores were already in the matte medium to start with and when water was added the diluted solution provided the right conditions for mold growth. Finally, the mold had to have something to eat and it ate the polymers and other materials in the matte medium so it’s not going to be good for much now. Oh, and in another life I was a PhD microbiologist bur now I’m a happy model railroader.
Mold spores exist everywhere. Add the right amount of moisture (i.e. a sealed, breathable container like a 1/2 gallon ice cream carton) and mold will grow. The same thing happened to me with a small bucket of drywall tape mud. I let it sit for 6+ months. Opened it to make a patch somewhere…almost vomited it smelled so bad.
I think I’ll go the safe route and throw it away. The original bottle (about half full) has no mold, so I’m going to guess it was a mixture of tap water and whatever was on the Supertrees, despite being boiled.
It depends in the level of treatment. Mold spores are one of the hardest microbial forms to kill and the amount of disinfectant need to insure complete kill will render the water unpalatable. Also, the water can be contaminated downstream in the system especially in older systems. The amount of residual chlorine or chloramine left in the water may not be sufficient. That’s why yo
A while back, I took a class on home remodeling. The contractor who taught the class told us about one of his clients who complained about there being a moldy smell in her bathroom, with no apparent mold. It turned out that the wallpaper in the bathroom had been hung with a flour and water paste, which the contractor described as “the perfect medium for mold growth”, and the mold was growing under the wallpaper. The contractor then advised us to always use an acrylic paste that wouldn’t support mold growth.
So the thing that puzzles me is how the matte medium could support mold growth. I’d think the medium would be made out of something that wouldn’t provide the nutrients to support mold growth. I am a bit more puzzled because Tyler says in the OP that he bought his matte medium from a paint dealer, and I would think products sold for home improvement would be designed to prevent mold growth.
Matte Medium is almost a flour/water mixture…and, if it has not been let closed can get mold…
Acrylic paints…if left in open jars for extended periods of time may get it as well…
Q: I have some old acrylic paint in jars, and I think some of it went bad. Is it still ok to use? A: While acrylic paint has a relatively long shelf life, if it’s been diluted with tap water and stored, foreign material has been left in the jar or containers have been left uncapped for extended periods, mold can result. Badly contaminated paint should be discarded, but if the majority of product seems unaffected, visible mold can be removed and discarded and a capful of ammonia added to retard further growth. Back to Top.
In and of itself, matte medium cannot support or promote mold growth. Mold is essentially propagated by air borne spores. When the spores come into contact with water, it is the oxygen component of water that supports and promotes mold growth. Once water is mixed with matte medium, it only needs a food source for mold to grow. That can be anything from wood to fabric to drywall, whatever.
According to Liquitex, a manufacturer of matte medium, it is an acrylic polymer resin. It can be emulsified with water. Once emulsified, it will adhere to anything – from canvas to paper to metal to wood to plastic– and it dried quickly. Most important, it can be thinned and cleaned up with water.
I just soaked a turnout overnight in water and liquid dish detergent to remove matte medium. The turnout had been on my layout and had been ballasted and held in place by a mixture of matte medium and water. After soaking, I was able to restore the turnout to like new quality.
Which raises the question, as we all get bored to death, is Elmer’s Glue a polymer emulsion. According to the Material Safety and Data Sheet for Elmers Glue, it is a liquid polyvinyl acetate (PVA) emulsion.
No matter what the material the key is usually moisture. If us mix glue wiht water the mixture is usually dry in a relatively short time. It’s when the material stays damp or moist that mold has a chance to thrive.
Have you fellas’ ever looked in an old container that got lost in the nether-land at the back of your refrigerator for a month or seven? You will find the most weird and wonderful Aliens in some of those containers. I am willing to bet that the cause of the problem was not with the Matte Medium, the water or any of the materials that were used. My opinion, (for what it’s worth) was that the Ice Cream container had not been thoroughly cleaned with a strong dish detergent and HOT water to get rid of ALL Ice Cream residue in all the little nooks and crannies.
As for the stuff that you dipped in the solution, it may or may not come back to bite you where you sit. If they are all bunched together and remain damp for a period of time, it may start to grow funny looking fur. If it is well dried and the area in the basement is reasonably dry, it may be OK. As a precaution, I would give all the stuff that you made a thorough spray of a fairly strong Bleach or Lysol solution. Before you spray all the material, just do a small test patch to make sure that you don’t get funny coloured scenery.
Oh, that’s sweet Crandell! I get mold and gunk in the coolant for the machine tools at the shop and I’ve been using bleach but it causes other problems. I do believe I’ll try me a batch of the sodium meta-bisulphite. Never thought of that, but I’m not a beer maker/drinker. Thanks a bunch.