Q's about working with foam - handling, etc

Mark42

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Oct 8, 2003
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I am thinking of filling in the area on either side of my fuel tank with foam. Plan is to make cardboard form, line with trash can liner, and pour foam in. Then the cardboard can be tossed, the bag can be pealed off, and the foam block glued back in place and covered with carpet, etc. <br /><br />I have a few questions about working with foam:<br /><br />- Does it cut nice with a bread knife? <br />- Will an electric carving knife do a nice job of sculpting it?<br />- When it expands, does it build much pressure (will it break my cardboard forms if open on top)? <br /><br />Thanks,<br /><br />Mark.
 

ColdFire

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Nov 6, 2004
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Re: Q's about working with foam - handling, etc

Mark,<br />I didn't have a chance to try this with a large area so this is just my observations with 2lb. foam:<br /><br />- Does it cut nice with a bread knife? <br /><br />You can try but I would go with the carving knife.<br /><br />- Will an electric carving knife do a nice job of sculpting it?<br /><br />Probably but you will throw it away when you are done. A reciprocating saw would probably be best for 4 lb or heavier.<br /><br />- When it expands, does it build much pressure (will it break my cardboard forms if open on top)? <br /><br />I think if you do small pores it will be fine.<br /><br />Also with the trash can liner you might find it harder to peel off than you think (it is sticky, sticky stuff.) I needed a couple of working voids in my foam and I tried both saran wrap and a trash can liner and the foam stuck good enough to them that I ended up trimming and leaving it in place.
 

Moody Blue

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May 24, 2004
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Re: Q's about working with foam - handling, etc

Working with the foam once cured is very easy and precise. I used a (wood) hand saw to achieve large flat surfaces and a piece of 2x4 wrapped with coarse sandpaper to sculpt shapes and curves. Fast and simple but messy. Keep the shop vac handy.<br /><br />As for the cardboard form, I would use something with more rigidity. I don't think it will burst but it may distort somewhat. The other issue may be heat. In a large volume, a tremendous amout of heat will be generated. Might be best, as mentioned above, to pour in stages. As for the bag liner .... that foam will stick to EVERYTHING and you won't be able to separate the bag from the foam. Might try using a heavy duty vapour barrier plastic (polyethylene) with more success.
 

Mark42

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Oct 8, 2003
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Re: Q's about working with foam - handling, etc

Thanks for the tips guys, just what I needed to know. May have to use the saw and cut the bag off. That would leave nice flat surfaces that a layer or two of fiberglass could cover. It needs to be protected from getting kicked and beat up by the people in the front seats.
 

Realgun

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Jul 31, 2003
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2,484
Re: Q's about working with foam - handling, etc

I can tell you there are 2 blocks of foam under my dash. The Plywood was sealed to the floor and sides of the boat with a hole to pour into. The total poured was .80 Qts. This is what I worked out. In five minutes you could see the foam rising very close to the pour hole. You could here the plywood straining to hold the foam. After 2 hours my wife and I came home from lunch and the sides of the boat were HOT from the foam.<br />I am talking about 130 degrees hot.<br /><br />Also I got my hand in that foam too with no gloves! Its hot, sticky, and will not wash off had to wear it off. <br /><br />Any tiny hole will let the foam flow through it and not where you want it to be.
 
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