Instructables
Picture of 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 significantly. 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.

 

 
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Step 1: What you will need

Picture of 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

Pour 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

Picture of Experiment to verify effectiveness
IMG_2042.JPG

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 melt and drip.  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.
Majornav9 months ago
Great instructable!
Most recipes include adding boric acid to the solution.