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DIY Mold-Control and Prevention Spray

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#1 TVCasualty


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Posted 11 September 2019 - 01:52 PM

DIY Mold Control and Prevention Spray-On Treatment


To 1 quart of hot water add:


  • 1 Tablespoon baking soda
  • 1 Tablespoon washing soda (aka sodium carbonate)
  • 2 Tablespoons TSP (trisodium phosphate)

Add the dry chemicals to the water and shake the hell out of it. Vent the slight pressure build up a couple of times while shaking it if using a bottle. Put it in a sprayer, and apply. You're done! Wear gloves and eye protection; don't get it on your skin (it's irritating) or in your eyes! It's safe to touch treated surfaces when they've dried, and only becomes effective when dry. It will darken unpainted wood a little, in case that's an issue.
When treating a large area, I use a 2-gallon garden sprayer with the nozzle set to a fine mist to apply it so I just multiply the formula by 4 to make a gallon and mix it directly in the sprayer (no need to vent since I'd have to pressurize it anyway).


Try to use the finest mist possible; you don't need to saturate surfaces so they're dripping, just get them covered and a finer mist stretches your mix further.



I wanted to pass along the formula for a home-made version of the retail product known as Concrobium (sold at some hardware stores). I've been posting it in threads lately and thought I should just make a post I can link to from now on since I think everyone needs to know about this even if they don't grow fungi because mold is a very common issue and bad for our health regardless.


I found the above formula while searching online for the MSDS and the original Patent for it and found a blog where a research chemist had already reverse-engineered it, saving me the trouble and a lot of money!


It costs something like $2 dollars/gallon if you mix it yourself but $35/gallon to buy the retail version (which also happens to be ~98% water!). It was the ridiculously-high cost that inspired my search; if they'd been less greedy when pricing it I probably would have just bought it retail.


Since I can make it so cheaply, I went ahead and mixed up 6 gallons of it and used an electric chemical sprayer with a really long hose to spray/treat every surface of my once hideously moldy crawlspace. That was a nasty, rough job but very much worth it.


I sprayed it directly on to visible mold in some places, which it killed and it has not regrown since (this was several years ago). I also re-covered the bare dirt in the crawlspace with a new layer of thick plastic sheeting to minimize humidity. The old stuff had been torn up and was falling apart, so the dirt was exposed making the space very humid as the ground almost never dries out.


And here's some more good news: As long as it is not washed off, it will remain effective indefinitely and works via osmotic pressure on mold and mold spores (like salt, only much better).




NOTE: Some of you will have trouble finding TSP.


It is no longer sold in some areas and has been removed from laundry detergents and other cleaning products due to environmental concerns because phosphates in runoff feed algae blooms (it's a nutrient pollutant). But this use of it won't be discharged into a watershed so no need to feel guilty about it.


It can be ordered online if necessary, and the commonly-available TSP-Substitute will NOT work, so don't use that instead. Most TSP substitute comes in liquid form while the real stuff comes in a box; don't use the liquid.


It might even be banned and taken off the market completely some day so it wouldn't hurt to stock up just in case, and a 16 oz. box goes a long way.



Well there you have it! Hope this helps; if you use it, it will.

Edited by TVCasualty, 11 September 2019 - 02:01 PM.

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#2 TVCasualty


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Posted 11 September 2019 - 01:56 PM

Metric version:


To each liter of hot water, add:


  • 15 mL baking soda
  • 15 mL washing soda (sodium carbonate)
  • 30 mL TSP

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#3 Juthro


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Posted 11 September 2019 - 06:08 PM

Another fun fact, TSP is the active ingredient in most chimney creosote reducing logs that you burn in your fireplace to make the creosote in your chimney dry, crumbly, and non flammable.  :)


I get mine from the paint section of the local hardware store, as it's used for cleaning and prepping surfaces before painting.  If you can't find it in your area, amazon delivers.

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#4 sandman


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Posted 11 September 2019 - 08:51 PM

I've got a spot that keeps popping up on a baseboard that I will try this on. Thanks.

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