Home Cleaning Tips Homemade Mold/Mildew Stain Removal Gel

Homemade Mold/Mildew Stain Removal Gel

by Catherine

Because I am often in mad scientist mode now that I have started this blog, writing and experimenting with products and techniques to find which things clean for mold best, I sometimes end up making products that once I have them, I don’t know how in the world I didn’t think of “inventing” them sooner. This cleaning gel is one of those inventions.

Before I begin telling you how to make it and what I use it for, I want to make sure that you know something about me. I take reader comments, input and suggestions very seriously. If a reader finds something I post helpful or informative, disagrees with something, or wants me to post more about a certain topic or cleaning technique, I want to hear about it. So, this post is the result of a recurring reader question concerning the EC3 Mold Solution Spray and hard to remove mold/mildew stains on grout or tile. People love how the EC3 Mold Solution Spray wipes out the existent mold and eliminates the mycotoxins created by some of the more dangerous molds on contact, but they don’t love the way that the product leaves visible mold and mildew stains behind. In other words, you have to physically scrub the stains out, because the product does not bleach or lift the actual mold stains without a little added elbow grease. I addressed that once before in my post, How to Remove Stubborn Mold and Mildew Stains from Grout, but many people wanted to know if there was more of a “one stop shop,” or one product that could do it all without so many steps, and hard work that they could use. I am one for simplicity myself, so I went about trying to concoct a product that would “do it all,” so to speak.

This was harder than I thought it would be. Bleach, even though it is highly toxic and has been shown to only be successful in killing surface mold, seemed to be everyone’s go-to for the stains, even though they knew it wasn’t the smartest choice. To find out more about why not to use bleach to clean mold, read my post, My Case Against Bleach for Cleaning Mold. No one wants mold stains—even when you know the mold has been rendered lifeless by the EC3 Mold Solution Spray.  I agree completely and do not want to see the stains of the mold as a lovely reminder of its former existence.

After testing almost every combination I could think of, I finally found the winner. Not only does it successfully stamp out the mold and remove any traces of its stain, it also won’t emit harmful fumes when you are stuck in that bathroom using it. And, while I designed it to use on tile and grout, it works just as well on non-porous surfaces. It has now become my go-to for my bathtubs, sinks and for cleaning my stove top. I have been using it religiously now for a week, and I cannot believe that I didn’t think of making a product like this sooner.

Mold Stain Removal Cleaning Gel

(I am calling it a gel, because it has what I call “cling” action. It is viscous and will stick to the area where it is applied for greater penetration and more targeted application. As a result, you do need to sponge or rinse this product off, unlike when you just use the EC3 Mold Solution Spray, and can just allow it to air dry without rinsing it off.)

Ingredients & Tools:

Here is everything you need to make a great mold-killing, stain-lifting “gel” to use for many cleaning tasks in your home.

  • 1/2 cup distilled water
  • 1 Tablespoon guar gum or 2 Tablespoons cornstarch (The guar gum will make it into more of a gel, and the cornstarch into more of a paste, so use whichever you prefer.)
  • 3 Tablespoons EC3 Mold Solution Concentrate
  • 3-4 Tablespoons Borax—I use the 20 Mule Team Borax that you find with the laundry detergents in the grocery store. (Note: Borax is only toxic if ingested, so make sure to keep the Borax and Mold Stain Removal Gel you are creating in a place where children CANNOT reach it.)

Borax is a great tool to keep around the house. It works great as a laundry booster, a deodorizer and an abrasive scrub.

  • Small pan
  • Bulb suction syringe (I just used our turkey baster. It worked like a charm.)
  • Empty and clean glue squirt bottle or other type of squirt bottle with a top that seals closed. (I purchased mine at Target in the section where they sell empty travel-size toiletry bottles.)


  • Mix the distilled water and cornstarch or guar gum together in the small pan. Turn the burner on under the pot and bring to a boil, stirring constantly until mixture begins to thicken. Continue to stir until the mixture reaches a pudding-like consistency. I use a wire whisk the whole time, because the mixture tends to form lumps, and whisking it will help dissipate the ingredients. You will know when the the mixture is ready, because it will coat your wooden spoon nicely.

Whisk the water and the cornstarch or guar gum constantly as it begins to boil to keep the mixture from clumping too much. You can see it thickening and forming its gel-like texture on the side of the pot.

  • Remove pan from the heat and allow mixture to cool completely. This is VERY important. I had to throw out a few pots of this, because I would try to add the Borax and EC3 Mold Solution Concentrate too soon. It would clump and separate, not giving me the consistency that I wanted.
  • Once cool, start adding the EC3 Mold Solution Concentrate, and Borax alternately, one tablespoon at a time—one tablespoon of EC3/one tablespoon of Borax. Stir each addition until incorporated.

The Borax and EC3 Mold Solution Concentrate should be added 1 tablespoon at a time. You also should continuing the whisking action to keep the gel smooth.

  • For more “bleaching” action, add a few tablespoons more of Borax than EC3. Once gel is the desired strength and consistency, use your bulb syringe (aka turkey baster) to suck up mixture and squirt it into your empty bottle, until bottle is full.

Once the mixture is nice and smooth, and is at the stain-lifting concentration that you desire, use your bulb syringe to suck it up and squirt it into your bottle for later use. There may be a little liquid that separates once it is in your squirt bottle, so just give it a good shake each time before you use it.

  • Label outside of bottle with a marker, so that you know it contains your Mold Stain Removal Gel.
  • Use as desired.

Now that you have made your super-duper Mold Stain Removal Cleaning Gel, you can start tackling your grout or anywhere else you need to lift a mold/mildew stain.

Here is a close look at an ugly mildew stain on the white grout in my guest bathroom. It needs to go!

I just squirt the gel directly onto the grout. I allow it to penetrate for 2-5 minutes.

I am very generous when I squirt the gel on the grout. It is okay if it runs down into the tub. You can just swish it around with some water and clean the tub too, while you are at it.

Once the stain has lifted and the area is no longer discolored, I use a clean sponge soaked in warm water or I use the nozzle of the shower to rinse off the area. Of course, if you want to use elbow grease, go right ahead, and scrub the stain off. There is really no need to, though, because the stain will lift without the scrubbing. Depending on how old the stain is, you might need to adjust the concentration of your gel accordingly. The beauty of it is that you can make it to serve your needs without worrying about increasing the toxicity or it hurting your tile or grout.

As I wipe the gel away, you can see how much just one 2 minute application lifted the stain. I didn't even scrub!

Just to see if this worked on other types of stains, like paint and nail polish, I used it like you would use a Clorox Bleach pen on a nail polish stain on a Corian countertop. I had unsuccessfully scrubbed and scrubbed at this stain with everything in my arsenal many times. With my new gel, the stain completely lifted on the area where I applied it. This just goes to show that it does effectively wipe out stubborn, penetrated stains.

Here you can see the purple and red nail polish stains on the Corian counter.
I apply the Mold Stain Remover Gel generously.
I wet my sponge with warm water and wipe, applying some pressure to the stain. The purple comes right out.
With a few more wipes, the red nail polish stain comes right out too. I didn't even have to wear gloves, because there was NO bleach invloved.

Give it a try! Let me know how it goes, and if you have any questions or concerns.

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Raquel Ramos April 24, 2021 - 8:34 pm

Hi, I tried this recipe with cornstarch. Once cold, it becomes a kind of plastic, there is no way it will be a pudding again. So the mixture with the cleaner and the borax kept separate, like lumpy and foamy.

Catherine May 12, 2021 - 3:46 am

I usually make it and use it. I mark the applicator or container that I use to make it, so that I don’t use it for anything else. Natural products are much harder to keep. You will always have to store them in the fridge. I like making enough to use and just doing a big clean.


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