I'm trying to apply some expanding foam to the inside of a closed
garbage bag that's situated between two surfaces that are about an inch
apart. I want the foam to take the shape of the irregular surfaces as
it expands and hardens, but I don't want the foam to adhere or bond to
these surfaces so I've placed an ordinary plastic garbage bag between
them and that's where the foam is being injected.
I'm discovering that the small amount of foam that's leaking out of the
fill-holes is expanding and curing nicely, but the foam inside the bag
seems to be semi-solid goop. I'm leaving this over night to see if it's
any better tommorrow, but I'm thinking I'm going to need a different
sort of product other than "Big Stuff" aerosol can gap filler.
I know there's some foam packing material that is isin't particularly
messy and I think is applied inside a bag or membrane that conforms to
the shape of what-ever is being shipped. Is this stuff available?
Any other ideas?
I see that there's 2-part expanding foam that comes in variety of
densities, for marine use, hobby, etc.
So you mix 2 parts, and you have maybe 30 seconds or a minute to pour it
before it starts to expand.
The stuff you buy in an aerosol can - is that 2 parts (and if so, how do
they keep the 2 parts separate)?
Somebody at work just told me about this stuff, I'd never heard of it.
Totally new to me.
I always figured that "foamed in place" packing required an expensive
setup; tanks, hoses, etc
You might try making your bag "tall" and leaving it open on the top
Maybe that allow enough access to atmosphere to cure.
Play around with the volume of foam you squirt in and let it "grow"
towards the open edge.
If you get the amount correct you won't get much excess height.
The excess can be trimmed off with a utility knife
Seems like the key is using a plastic bag that is not completel
Maybe yours will cure overnight.
Yea, that's what I was thinking about. I've seen that sort of packaging
material at work (we've received stuff that was packed using either
exactly that product, or something that worked exactly the same way).
If you notice, that is a 2-part expanding foam product. It's just a
I still wonder how the single-part "foam in a can" works compared to the
The foam-in-a-can seems to need exposure to ambient air in order to
expand and cure, but the 2-part stuff doesn't.
I don't think I'm going to be able to source any 2-part foam locally.
The best shot seems to be a hobby or marine products store. I don't
think any of the big-box home improvement stores have this stuff.
I'll probably have to modify my setup so that I can spray the
foam-in-a-can with full exposure to ambient air.
Urethane foam requires moisture to set. In a sealed plastic bag there
is no moisture, so it never "kicks off" the reaction. You could try
misting the inside of the bag lightly with water before injecting the
You are on the right track, but I don't think anybody sells one-use
packs of the stuff- it is usually a station on the packing line, fed
from tanks. I don't suppose your project is portable enough to carry
into one of those shipping places?
If your concerned if it will set up inside, try a test. I have added foam
to Coleman coolers and the like. I may take a day or two. It sets up
internally when you make a ball, so I don't think it need air.
All the small cheap coolers have no insulation in the top. Heat radiates in
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