Our old freezer had to be unplugged for a few weeks, and the inside grew shockingly moldy. For reasons to do with the safety of various pets in the house, we cannot use chlorine in this particular space.* I’ve heard it said that hydrogen peroxide would work, but tried it and got nowhere.
I’ve been going after it with 99% isopropyl alcohol, spraying it down, letting it soak, and then wiping. I’ve been through several iterations of this, and it is mostly clean. But there are still some stubborn areas, and unreachable niches, and the whole thing still smells horrible. No way I want to keep any food in that.
Does anyone know of a good chemical to use? One that: won’t put off noxious gasses that float off to kill delicate birds and fish; is safe to use in food storage spaces; and won’t eat holes in freezer plastic and various metal parts?
Thank you for any ideas you may have.
*Please don’t get into an argument about why it’s ok to use chlorine. We’ve lost one fish to that, it ain’t happening. We need new suggestions.
I used a melamine sponge on stubborn mildew in the shower, a prefab acrylic enclosure. It was my last resort and it wiped away like magic. I threw everything at it and only the magic eraser cleaned it.
You may never get that smell out. Plastic is porous enough that it’s permanent. You can scrape the surface clean but to have any chance you need something that will penetrate the pores in the plastic, and it will have to sit there for some time. If possible, take the freezer outside and use chlorine bleach.
Put a whole lot of baking soda in it (baking soda, not baking powder); forming a paste with water to get it to stick in nooks and crannies, but also just dumping a lot of it in. Let sit a couple of days, then wipe and vacuum the baking soda back out.
Worth trying. Might work.
(Right now baking soda’s kind of hard to find around here, though. Hope it’s a local shortage and not affecting your area.)
Too late to edit: I don’t know for sure whether large quantities of baking soda give off anything that affects fish. Baking soda all over the floor doesn’t seem to bother cats any, FWIW, though I’ve never shut a cat in a small enclosed space while doing this. You could close the freezer after you put the baking soda in it.
Turn the freezer to the coldest setting to kill the mold
Use a wallpaper steamer to steam away the mold
Create a paste from water, baking soda and salt and coat the moldy area for a long time. Maybe coating the whole inside of the freezer will help remove the odors.
Concrobium Mold Control is a solution of TSP and Sodium Carbonate + various food grade salts and deionised water that disrupts the mold and mildew spores by mechanical destruction when the solution dries. Neither main active ingredient is volatile and shouldn’t cause harm to pets short of spraying them down with it, allowing them to drink it, or swim in it. We sell a lot of it where I work (Pacific Northwest vacation community, closed up cabins just breed mold). Just perused the MSDS and like most SDS’s it appears dire but reading between the lines it is pretty innocuous stuff aside from the high pH (wear gloves and goggles when spraying). Directions for use are to wet down affected surfaces, allow to dry, then wipe off. Re-apply and leave the residue for prevention of regrowth if needed.
Bro thought he was having a problem with black mold. His research indicated that ozone might kill it. But it turned out he was ok so he didn’t proceed with any remedies.
You know, I hadn’t thought of just scrubbing it down with salt. Great idea! I do have a steamer but I’m afraid of what it might do to the walls. AIUI plastic that is formulated to not shatter in cold temps usually melts pretty easily. UV light is also a good idea. As for cold, I don’t want to turn the freezer on with this mold in it, because then the spores will get blown out all over the place. And it’s right next to the HVAC intake.
I can definitely try vinegar. I will read up on bromine and Concrobium tomorrow.
Saving UV and ozone production equipment for last resorts.
Anybody know anything about Steramine? I know that commercial kitchens use it, it’s food safe, and it kills mold. But is it volatile? (For mold, scroll to the very end)
If - or when - you’re satisfied that the mold itself is gone and it’s just residual odor, activated charcoal is another good option. It’s what they use for aquarium filters - in fact, the fish supply aisle is a good source for it.
Let it sit in a closed freezer, then wipe or vacuum out.
Note: quick lighting charcoal briquettes are NOT the same thing, and you’ll simply trade one stench for another. True story.
Why would the spores get blown all over the place? Other than a small drain hole at the bottom that you can plug, there’s no (intentional) exchange of air from outside to inside the box.
Something else that may be causing your problems is that if this is the type of freezer with an evaporator coil inside it**, they can get covered in mold. You can scrub the exposed surfaces all day long, but until you pull the back panel off, you’re not going to get anything back there.
**Sometimes the coils are inside the walls, if this is what you have, you’ll normally see ice forming on the interior sides of the freezer. Sometimes the shelves are actually the coils If there are fans inside the freezer and you can feel air blowing, you’re going to have to get to the coils and clean them as well.
Steramine is a quaternary ammonia product. This group of products (commonly called “Quats”) are generally considered safe, but are poisonous. They do have procedures for food contact surfaces (at low concentration) that they consider no-rinse, but it requires longer contact times. When I worked as a microbiology lab tech, we used it all the time without regard to being hazardous (this was in the late 70s) and never had any issues. It is widely used in hospitals for general disinfecting and is one of the more common disinfectants used to protect against the corona virus. Chances are very great that you have been exposed to it if you have been in any public area within the past 8 months. Based on my experiences, I would recommend it. In fact, I opened this thread to recommend that you try quaternary ammonium disinfectants. I would not put any in a fish tank or use it on food contact surfaces without rinsing. With rinsing, I would have no reservations.
Bear in mind, these compounds do contain chlorine, and quaternary ammonium compounds are nasty. They are formed when you mix ammonia and chlorine bleach. Yeah, that nasty. However, the specific compounds used in the disinfectants are stable and have been used safely for decades. Use as directed, wash your hands after use, and do not feed to pets or children and you will be fine. Just remember that it works by killing and that anything that will kill single-cell organisms will also have the ability to kill multi-cellular organisms. Unlike vinegar, hydrogen peroxide, and other “homemade” preparations, it is very effective and it won’t degrade the plastics as badly.
Another possible solution would be to use Provodine Iodine, as you can get from the drugstore. One teaspoon per gallon is effective, but it will stain plastic brown.
