Homemade Flame Retardant





Introduction: Homemade Flame Retardant

This is my first instructable, so please bear with me. Many times in the course of building / re-purposing items for various projects I have encountered a need to add some level of flame resistance to certain elements of the project.

While this procedure won't make any items flame proof, it will minimize the probability of ignition. In this tutorial I will offer a possible solution for flammability problems along with the recipe and the results from a quick and dirty experiment. This technique will only work for natural materials such as wood, cotton, jute, and paper or the like. It will not work for synthetic materials such as polyester, nylon, polypropylene or anything else that did not originally come from a plant or tree.

Step 1: What You Will Need

Borax (sodium borate) laundry booster

A measuring cup

A 1 Tablespoon measuring spoon

An old sauce pan

A storage container

Some sort of applicator ( paint brush, spray bottle, etc)

Step 2: Procedure

You want to make a saturated solution

Boil 1 cup of water

Add 2.5 tablespoons of Borax to the boiling water

Stir until the Borax dissolves

Allow to cool to room temperature. Some of the Borax will precipitate out as the solution cools. This is normal, the clear liquor left is the flame retardant mixture.

Pour the clear liquid into storage container or spray bottle.

Step 3: Application

You can use a spray bottle or brush

Wet the heck out of the item to be protected. Make sure it is saturated.

If you run out of solution, make more, because the item has to be absolutely positively soaked.

When you think its wet enough, wet it some more

Allow to dry

Once the solution dries, it is very important to keep it dry as any water contact will wash the protection off.

Step 4: Experiment to Verify Effectiveness

Experimental Design:

Two 11” x 1” wide strips of printer paper were cut. One strip was soaked in the flame retardant (FR) solution for 5 minutes to ensure total saturation of the paper fibers. The other strip was used as an untreated control. The treated sample was removed from the solution and hung up to dry overnight. The untreated control was kept in close proximity to the treated sample to ensure that both samples were exposed to the same environment and that the only difference was the Borax treatment.

After drying overnight, the treated sample was cut into 3 roughly equal sections and the control was treated in the same manner.

Each specimen was then gripped in along handled pair of needle nosed pliers and lit with a match.

In every case the untreated specimens were completely consumed by the flame while the treated specimens smoked, generated a char and then self extinguished (right 3 specimens). Below is an image of the final results. In this image, I was only able to transfer the ash of one untreated control sample ((left side of the image) to the cardboard for the photograph, the other two controls disintegrated.

This works because the borax forms a primitive form of glass as it is exposed to the heat of the flame. The glass acts as an insulator, protecting the paper fibers from the heat and allowing them to char instead of burn. The char acts as an additional insulator. Eventually there is not enough heat to support combustion and the fire goes out.

Step 5: Final Comments

This will only work for natural materials, synthetics will not form a char, they will burn, melt and drip and set other things on fire. Once the solution is applied and dried it is important to keep the protected item dry or the protection will wash off. While I have used this method successfully in projects as varied as shop bullet traps to paper decorations, your mileage may vary.

Please do not use this info as a substitute for common sense.



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    Would this work on Crayola Air dry clay?


    Borax has excellent solubility in water. It is used as a laundry chemical - it wouldn't work at all if it had poor solubility.

    Borax has very poor solubility in water, Borax and Boric acid together are water soluble,this mix will work much better. Try 4 parts Borax to 3 parts Boric acid.

    Tim Hargreaves - Shark Bay, WA Pastor also known as Hargreaves the Handyman.

    Well done mate - I don't know the chemical make-uo of Borax but if as I suspect there is a salt factor then SALT is a good fire inhihitor. The Tamarisk tree sheds a high quantity of salty resin & trying to burn the needles it sheds is extraordinarily difficult just as is the case with seaweed.

    Repetitive spraying of palm fronded partition walls - as likewise any other flammable material - with plain old sea water is a cheap way to help with fire-proofing materials. This of course is against the initial fire risk of a casual flame. At the end of the day almost NOTHING can withstand fire in its extreme expression such as an oxyacetylene flame or a roaring bush fire..

    Thanks very much for this.

    We're in the earliest stages of making papier mache ceiling tiles for our home, and this will allay a few concerns.

    2 replies

    It should work well with papier mache. Are you planning ti add it to the mix or treat the tiles after they are finished? Thanks for the kind words

    I'm on the fence about that- the spray approach would be less iffy to the formula, I'm thinking, but also less convenient/ thorough. We're still experimenting with our goop formula, although we're doing a first "final" tile today. Thinking I'll add it to the "goop" at the tail end of the cooking process, today, just before running it through the chopper to make it into "clay" [and adding the dyes]. I"ll share photos later if you like.

    Just great!...Can this be used on wood?, is there someting you can add or finish off that will make the product stick or adhere better or permanently?

    2 replies

    It should soak into wood, but would likely take a good bit.


    Yes it can be used on wood. It should soak in somewhat. I am not aware of any finish but you may be able to add it to a waterbased paint,

    Wow, just read through the procedure and comments. KUDOS to you folks all around. I am a forensic science teacher in Modesto, and we are using your formula and method to have the students investigate the recent Ghost Ship fire. Specifically, after examining the facts so far in the far over five sources, and answer the standard "who, what, etc for all, then compounding retardants to see if this process would have provided a measure of protection for the inhabitants (not encouraging the apparent failure on several parties and levels to provide common sense hazard mitigation). Thank you for posting folks!

    2 replies

    Thanks, I'm glad it is useful


    Excellent! Thank you!

    FYI...when I applied this to our curtains at our school and the fire inspector showed up, he said that this was not acceptable unless it was tested by a laboratory with a copy of the test report. So, I wound up purchasing a fire retardant called Flamex PF which worked better than this formula and was accepted for code.

    5 replies

    Good to know. Thanks for letting the community know. In general it is a good idea to use 3rd party certified products when in a public environments.

    Brominated flame retardants are very effective. The Flamex PF you mention uses ammonium bromide instead of Borax.

    Not sure where you got your information from but our Flamex PF does NOT contain bromides! Don't post things that you're not sure of since you may be held liable.


    Not sure what I can be liable for. Although I did make a mistake and referenced a product from Rosco called Flamex PA, not Flamex PF.

    Perhaps you should be more concerned about another company operating in the FR space with a product with an almost identical name than trying to bully people who write instructables.

    I took a look at your vague MSDS and based on the decomposition products, I think I have a pretty good idea what your "proprietary" materials are. Perhaps I need to upgrade this instructable to use a similar water soluble material.

    Below is a link to Flamex PA MSDS


    You tell him lol :-)

    I actually appreciate the time and effort you took to put this together, and I thank you for doing so. I do think people (mnn) should also try and make light of fact that this person has gone out of their way to compile information to help others, rather than trying to beat them down.

    Kudos to you Author :-)


    Thank you

    Thanks for letting the community know. In general it is a good idea from the point of view for the chemistry.


    BTW Rosco Flamex PA comes up in a search at the top of the page,National Fire does not, I had to go to the bottom of the page to find your product. Also Rosco's MSDS was published almost a year earlier than yours.