Can I use spray foam to make a plug?

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Can I use spray foam to make a plug?

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Moto-Mucci	M Moto-Mucci posted 6 Years Ago Topic Details
M Group: Forum Members Posts: 2, Visits: 5	I'm looking to make some fiberglass motorcycle fenders of my own design. I'd like to be able to create the plug on the assembled bike so I can account for clearances. I was thinking the easiest way would be if I covered the front end in plastic, spray something like Great Stuff expanding foam all over the front tire and between the forks, then carve away. This seems like it would be much easier, cheaper and less messy than clay. Would the spray foam work well for this? Are there other similar alternatives? thanks, Dave
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Steve Broad	Steve Broad posted 6 Years Ago Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Moto-Mucci - 10/14/2018 6:57:27 PM I'm looking to make some fiberglass motorcycle fenders of my own design. I'd like to be able to create the plug on the assembled bike so I can account for clearances. I was thinking the easiest way would be if I covered the front end in plastic, spray something like Great Stuff expanding foam all over the front tire and between the forks, then carve away. This seems like it would be much easier, cheaper and less messy than clay. Would the spray foam work well for this? Are there other similar alternatives? thanks, Dave I used expanding foam to make the egg shaped plug for the front section of my exhaust cover. Sprayed the foam, trimmed to shape and finished with a fine body filler.
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Hanaldo	Hanaldo posted 6 Years Ago Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Simply put, yes you can. But it isn't the ideal stuff. As it is a single pack product, it takes a very long time to cure, and so isn't dimensionally stable. The larger the project scale you are working on, the bigger an issue this is. It also outgasses quite a lot, which can cause other problems. However there's no reason you can't spray it on, shape it as much as you want to, and then cover it with a layer of fibreglass. From there, the spray foam underneath won't have too much affect. Don't be surprised if polyester/vinylester resins attack it a bit and eats out a few holes, some of them are more chemical resistant than others so will depend on the specific product you are using. Would pay to do a small test first before covering your entire sculpted work and watching it melt. If it does react, give it a coat of epoxy first. Personally, I prefer to use the 2k expanding foam. The spray stuff seems so simple a solution, but for one it actually doesn't expand very much and you need a lot more than you think (and it's ludicrously expensive for what it is). The 2k stuff is a touch harder to use, as it is a pourable foam and hence you need to work out how to put it where you want it. But for jobs like this, I simply let it start to foam for 10 seconds or so, and then use a brush to slather it where I want it. It gets extremely sticky at this point, so it will stay there. Might take a couple of applications, but when it fully cures in 15 minutes and costs about a tenth of the spray on stuff, it is really more economical.
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Moto-Mucci	M Moto-Mucci posted 6 Years Ago Post Details
M Group: Forum Members Posts: 2, Visits: 5	+x Hanaldo - 10/14/2018 10:33:05 PM Simply put, yes you can. But it isn't the ideal stuff. As it is a single pack product, it takes a very long time to cure, and so isn't dimensionally stable. The larger the project scale you are working on, the bigger an issue this is. It also outgasses quite a lot, which can cause other problems. However there's no reason you can't spray it on, shape it as much as you want to, and then cover it with a layer of fibreglass. From there, the spray foam underneath won't have too much affect. Don't be surprised if polyester/vinylester resins attack it a bit and eats out a few holes, some of them are more chemical resistant than others so will depend on the specific product you are using. Would pay to do a small test first before covering your entire sculpted work and watching it melt. If it does react, give it a coat of epoxy first. Personally, I prefer to use the 2k expanding foam. The spray stuff seems so simple a solution, but for one it actually doesn't expand very much and you need a lot more than you think (and it's ludicrously expensive for what it is). The 2k stuff is a touch harder to use, as it is a pourable foam and hence you need to work out how to put it where you want it. But for jobs like this, I simply let it start to foam for 10 seconds or so, and then use a brush to slather it where I want it. It gets extremely sticky at this point, so it will stay there. Might take a couple of applications, but when it fully cures in 15 minutes and costs about a tenth of the spray on stuff, it is really more economical. I saw the 2K pour on stuff but assumed that application would be impossible for covering a round object and getting it to stay on the top side of the wheel without building some sort of container. I liked the spray on idea bc I can just blast it where I want it and build it up that way. I saw Smooth-on makes a spray 2K but the gun alone is like $800. Does anyone make a 2K aerosol? I know those exist for paint and clear coat (with the injector in the bottom of the can).
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Hanaldo	Hanaldo posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	The pourable stuff is perfectly useable on vertical surfaces, because it goes off so quickly. You've got about 30 seconds to mix it before it starts to foam, and then it foams for about 40 seconds before it starts to gel. So if you just mix it, and then let it start to foam for 10 seconds before using something to trowel it into place, then it will stay there.
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