Pourable foam

Has been well over a month since I submersed the foam sample in water. The piece weighed in at 7.7oz showing the weight increase of .2oz. Visualy the foam looks unchanged and fit back in its mold perfectly. The foam to touch feels very solid and about the same as the day I placed it in the water. I would say this disqualifies the theory that the foam goes soft in just a few weeks. I will continue the test for 1 year and will report the results at the 6 month point.
Regards
Bob C.

 

What did I do today:

I thought this was interesting. We have a UV / Wheather tester running 24/7. This is a unit, in which a couple of UV lamps burn for 4 hours, (temperature about 60 degrees C.)
the lamps switch of, and a condensation cycle begins, with 50 degree water and vapour.

I placed the following samples in the machine:

Epoxy foam (cast) of about 250 kg/m3
12,11 grams (I have an accurate scale)

Kapex C51.60 (extruded PU foam of 60 kg/m3)
10,05 grams

Herex C70.55 (PVC foam 60 kg/m3)
8,18 grams

Herex C70.75 (80 kg/m3)
12,43 grams

Let's see what the results are after a week.

What I missed was the following:
PU foam is capable of keeping liquid water out, but the cells are not water vapour tight!

 

Where do I get this? Can it be poured through a 1-2" hole? I just bought some off the defender site, and one part began expanding before I got to pour it! It ended up being a foam mountain behind my garage! I don't need but maybe 2.5 sq feet... perhaps three.

 

I can't stand to see people go nuts on foam. Owens-Corning makes BLUE dock foam billets. It is relatively cheap and holds up to normal amounts of oil, gas spills and some sunlight thru the dock boards. I think it is P V C. I called the Tech. Dept. and they covered their butts. Use it as stated was their public answer. It will survive a coating of hot roof tar as a roof insulation. A approved use.----------------Open 16' fishing boats use foam under the seats and transom, it is white. CALL boat companies and get the right safe answer. They are compling with the USCG, hopefully.

 

www.uscgboating.org---- Then Boat Builders handbook----then flotation---then flotation materials---Read about the pourable Polyurathane.

 

Maybe I'm just dense, but I cannot find anything referencing the polyurathane. Should I have not gone nuts over the foam?

As far as the blue dock foam billets... can i pour it into a cavity that i've already fiberglassed? I have a runabout that i replaced most of a stringer, as well as ~30% of the floor. I need to pour something into the left over cavity. i don't think i was going nuts when I assumed the product would be pourable for a bit. The defender website says the product would become "milky" after 3 min... not be fully expanded and SET!

 

Polyurethane by USCG standards meets ALL requirements, if of 4# density or greater when poured into spaces. I can copy and E Mail that page to you if you like. Let me know. Rich.

 

http://www.defender.com/product.jsp?path=-1|10918|16458|309319&id=21613

That is what i tried to use. one can began expanding as soon as i opened it. I was fully expanded in less than a minute.... I raced to try to combine both parts... but that was just insane. I've never done boat work before, but it shouldn't have done that right?

 

You got a BAAAD batch. Call them and tell them.

 

Just for the record. I wouldn't buy any boatbuilding materials from Defender. Shelf life is critical on many products used and I would buy from a more builder orientated store Like Composite One or FGCI http://www.fgci.com/

 

Hi Nassaw

What happend with your test?

 

Well it hasn't been quite a year but while the topic is up. I went and picked up the test piece from my lobster tank. Being my application is salt water I thought this would be a good place to submerse the foam. My first visual of the foam was the color had darkened and the foam felt harder than when first poured. Other than that I could see no change. I placed the foam back in a 1/2 gallon container and found its size hasn't changed. Placed it on the scale to find its weight had decreased 1/10 of an ounce. I calculate this loss to be blowing the surface area off with an air hose. I'll post pictures below. My conclusion at this time is the foam is closed cell and can be used for below the waterline application. being my rudders are already built I will replace the test piece in my tank and check when a year is up
Regards
Bob c

 

Hey Nassaw which foam did you use from the site? Is it the 8# foam?

 

Pourable Polyurathane Foam

This is becoming the hot product of the day. Home construction is converting rapidly as poly sandwiched between plywood is far superior to frame construction. Why is this important to boat folK? Price!!!!!! Companies are popping up all over that are selling poly foam in large quantities, the most popular are 5 and 10 gallon kits. Polyurathane, is fire proof up to 1000 degrees, super stong in high density 6 or more and the easiest damn product to use. When big Joe says, stand back I don't know how big this thing is going to get, he's talkin Polyurethane!!!!!!!! The best density to use is 2lb for floatation, yes the lighter the weight the more it'll float. 4 lb is starting to add a lot of strength, anything higher I would want professional advise because you could be wasting your money. To go from 2 lb to 4 lb you get half the volume but twice the strength, so yes it's 2 times stronger but cost twice as much, gets expensive real fast. Polyurethane is basiclly water proof but can absorb water if left submerged for a long time. If this happens simply cut out the bad area re foam and re glass.

One of the great features with this stuff is you can grind and sand it to shape and use polyester resin right on top of it. Just about any other type of foam will melt when polyester resin hits it, real ugly and the other stuff goes up in flames too, not nice!!!!

Polyurethane will produce around 14psi when expanding so be careful or you can blow the deck off or warp it real bad if it runs out of room to expand. If you find voids, cut the area open pour in some more foam and throw in the
cut out parts, the whole thing will bond together.

The folks that really know how to work with this stuff are the surf board builders. Polyurethane is the material of choice and board builders have been working with it since the 60's.

lots of questions answered here;

http://www.shopmaninc.com/faq_foam.html
http://www.shopmaninc.com/foam.html

board builders;
http://www.viser.net/~anthwind/Building/building.html
http://www.geocities.com/~kleb/windsurfn/buildboard/

Have fun, "But stand Back"

 

This is interesting but not true. "Pure" polyurethane foam--such as that attained by two-part fpourable oams--are very poor for boat building or surfboards. It is too brittle and has poor adhesion to fiberglass or epoxy resin. I speak not from theory but from experience; I have carved a number of boards and hull blanks from foam--and polyurethane is among the worst.

Only "blue foam" and "beadboard" make worse boatbuilding materials. All are only suitable for the roughest, short-lived projects. Also, you mention polyurethane's fire resistance. This may be accurate (I'd have to check) but it is also true that PU produces large amounts of extremely toxic gas at normal fire temperatures. It has been discontinued in mobile home construction for this reason. Last, just as with epoxies, any un-cured resin or especially hardner in the foam matrix is carcinogenic. Take precautions.

Dave