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Foam Flamability Testing

 

One foam,              
               two foam,             
                     white foam,
                                  blue foam:

Click photo to enlarge
With much discussion of the fire safety in using foam as a construction material for model railroad layouts and for scenery bases, we wanted to do our own testing to get to the bottom of the truth. Yes, we first reviewed the manufacturers ratings and other facts and opionions that others had posted, but we wanted to see our own results.

We wanted to perform a series of tests on two types of foam used for scenery base construction:

white foam - commonly called "bead board" because it is made of expanded foam beads. This is the type of foam that is used for packaging to protect products.

pink foam & blue foam - construction foam

To simulate different scenarios, we came up with four different tests which include:

1) Electrical overheating and sparks
2) The lit match test
3) Dancing flames beneath
4) Flames living on the edge

Disclaimer: All contents of this page and the tests described herein were conducted only for our own interests and not for advising anyone in the use or not use of any product mentioned or used in these tests. Therefore this information on this webpage should be viewed for entertainment purposes only. Do not perform these tests at home.

 

1) Electrical Overheating and Sparks
To simulate an overheating electrical device that would cause sparks and a possible fire, we used steel wool and a 6 volt lantern battery with a couple of test lead wires. we set a clump of steel wool the size of a cotton ball onto each piece of foam and teased it with the test leads from the lantern battery. Each ball of steel wool formed a hole in the foam as it heated and melted its way into the foam. No flame or continual smoldering occured on any of the foam with this method. The hole in the white foam melted much faster than the more dense construction foam.
 

2) The Lit Match Test
This test was to see what would happen if a lit match was laid on top of the foam material.

White foam - The lit match ignited the foam and it did not stop burning until the entire piece of foam was consumed. The smoke was black and thick. After the foam was completely consumed (in about 3 minutes) then the puddles of melted foam continued to burn with the same black smoke for approximately 10 minutes until they were all gone. The white foam ignited as easily as a wad of newspaper. The piece of test foam was approximately 10" x 6" x 1/2". The photo to the right shows all that was left after the piece of foam was completely consumed.

Pink and blue foam - These foams melted with the heat of the flame from the match, but did not ignite in flame. As you can see from the photo, the matches are completely burned from one end to the next. In executing this experiment several times, never did the foam want to burn, but only melt away from the flame to avoid it. Basically if the matches had burned longer, the foam would have continued to melt until the match either burned through the bottom and dropped, or sat upon whatever surface was beneath the foam. The pink and blue foam smell like burning plastic as they melt, but there was not really much smoke from the melting. Please notice the matches still in the holes in the foam. The hole in the middle of the blue piece in the photo is the remnants of the burning steel wool from test #1.
 
 

Click photos to enlarge   

3) Dancing Flames Beneath
This test shows the effects of a concentrated open flame beneath foam. For this test we placed a candle underneath the samples of foam with the flame in direct contact with the foam.

White foam - This material had another miserable failure as it just burst into flames and was totally engulfed in about 20 seconds. This also ended with thick black smoke coming from long lasting burning puddles of melted foam. Again, nothing was left of the foam.


   
Pink and blue foam - We were curious if a concentrated open flame would cause this foam to catch on fire. It did not. The heat of the flame simply melted away a hole above the flame until finally the hole was large enough that it went all the way throught the 2" thick foam. After the hole expanded to about 2cm (3/4"), the hole stopped expanding because enough heat was able to escape so the foam stopped melting.  Concentrated flame setup    


Resulting hole in foam

Click photos to enlarge

 

4) Flames Living on the Edge
An extreme test of flamability. This is the "let's try hard to make it burn test" by placing an open flame from a candle to the edge of the foam samples.

White foam - Of course this material had another miserable failure as it was totally engulfed in flames in about 20 seconds. This also ended with the previous thick black smoke coming from long lasting burning puddles of melted foam. We obviously have not had to try very hard to make this material burn and give off its noxious smoke and gases.


 

Pink and blue foam - This test amazed us at how the foam actually did not want to stay aflame by itself. We were able to get the candle to ignite the foam edge, but upon taking away the flame, the flames on the foam would extinguish themselves. This is true even when the foam was angled so that the flames had an optimal upward direction to try to keep the flames going. As you can see from the photo, we were able to burn away the corner of the foam sample, but this much foam being burned away was only the result of our catching the material on fire 20 times with the open candle flame. Each time, the flames extinguished themselves.

Click photos to enlarge   

Conclusion
White foam used for packing is as flamable as wads of newspaper, and produces a very thick black noxious smoke. Pink and blue construction foam easily melts, but it does not really like to burn. It basically tries to melt away from any threatening heat. The melting almost works like a safety feature. When this foam comes in close proximity or contact with threatening heat, it simply melts away from the area of the heat so that the heat is no longer a threat. Even if it is ignited into flames, without some other flamable material, it extinguished the flames on its own in our tests. The pink and blue foam also do not generate the noxious thick black smoke like the white packing foam produced.

After observing these tests, we actually feel safer about using the pink and blue construction foam now than we did before. We also feel that we will rethink ever using the white packing foam for filler in our model landscaping. From our tests, we theorize that if an electrical apparatus was attached to the bottom of a layout made of construction foam it would melt the surrounding foam until the weight of the apparatus would cause it to fall and either hit the floor or hang from the wires.

Now about those natural stick and weed tree armatures...that is a whole other set of tests.

Please note that these tests were only performed on bare foam. Once scenic elements such as turf, trees, structures, subroadbed, track, artificial water, and trains are added, the results may vary.

Disclaimer: All contents of this page and the tests described herein were conducted only for our own interests and not for advising anyone in the use or not to use of any product mentioned or used in these tests. Therefore this information on this webpage should be viewed for entertainment purposes only. Do not perform these tests at home.

 

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