Any spray foam that can expand / cure in a closed bag?
Home Guy
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?
Home Guy
> 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)?
aemeijers
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?
--
aem sends....
DD_BobK
Somebody at work just told me about this stuff, I'd never heard of it.
Totally new to me.
http://www.ivexpackaging.com/movie.php
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
edge.
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
http://www.yamahajetboaters.com/steveprice/tip6.html
http://www.ehow.com/how_7405490_use-canned-foam-packaging.html
Seems like the key is using a plastic bag that is not completel
sealed.
Maybe yours will cure overnight.
HTH
cheers
Bob
Home Guy
> Somebody at work just told me about this stuff, I'd never heard of
> it. Totally new to me.
>
> http://www.ivexpackaging.com/movie.php
Ivex Flaskpac.
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
self-contained version.
I still wonder how the single-part "foam in a can" works compared to the
2-part stuff.
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.
harry
The canned foam needs water to make it set. It gets this from the air.
So, in an enclosed space it won't go off unless you spray the surfaces
inside with water . Even then it isn't so good sometimes. It sticks
to damp surfaces even better than dry.
So you need to wet the inside of your bags. But even so, results are
variable.
If you spray the foam too thick/too big a blob, it won't go off,
remaining soft in the centre for a long time. The gas usually escapes
eventually leaving a big void inside.
The two part foam goes off regardless.
Frank
http://en.wikipedia.org/wiki/Polyurethane
Bubbles in the foam are from carbon dioxide liberated when isocyanate
reacts with water. In a two parter water could be in the polyol and two
parter is needed by op.
Home Guy
> >> 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'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
> > The canned foam needs water to make it set. It gets this from the
> > air. So, in an enclosed space it won't go off unless you spray
> > the surfaces inside with water.
> Decent article on chemistry:
>
> http://en.wikipedia.org/wiki/Polyurethane
>
> Bubbles in the foam are from carbon dioxide liberated when
> isocyanate reacts with water. In a two parter water could
> be in the polyol
So this morning the foam inside the bag was still a mix of ridgid or
cured/expanded parts and a lot of goo-ee parts. So I poured a couple of
cups of warm water in from the top, which saturated everything in the
bag for a short time before leaking out the bottom through some holes I
didn't know were there.
No detectable change in the goo factor.
So I take everything apart and put it on a horizontal surface and open
up the bag. Some expansion and curing did happen naturally, but the
water treatment had no effect. Most of what was there was skinned over,
encapsulating large pockets of goo.
When I broke the skin, it seemed to just stayed in a goo phase or state,
with no tendency to immediately start to expand and harden. Maybe this
will eventually happen if I leave it exposed to air for another few
days, but something has certainly changed the pace at which the goo
expands and hardens.
So there must be some time factor involved beyond just making sure this
stuff is exposed to ambient, humidified air.
> and two parter is needed by op.
Too expensive, and too hard to source locally.
DD_BobK
sprayed into bags.
I have no direct experience but it seemed like the links were
applicable esp the Yamaha one.'
cheers
Bob
cl...@snyder.on.ca
wrote:
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
foam.
gregz
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
all directions.
Greg
harry
>
> - Show quoted text -
If the foam is in too big a blob, the air/moisture does not penetrate
to the centre to make it go off. The goo in the middle is "unexpanded"
foam (ie lost its gas)
harry
>
> - Show quoted text -
cold and it won't set either.
jamesgangnc
> - Show quoted text -
densities. The 2lb stuff is porbably good for your project.
daha...@gmail.com
Clare Snyder
>Or don’t use an airtight bag. Have you considered trying a light linen or cotton based fabric bag?
soy based foams used for packageing.