JOHNBOY
Active Member
Any experiences with expanding foam makes types ect. 2 Pack or Tini type? FOR filling hollow rudder, for instance. is there a Marine special ?
Expanding Foam
- Thread starter JOHNBOY
- Start date
chippie
Well-Known Member
I recently investigated this subject for my boat. It is important that the foam be closed cell, or it will absorb water. I needed quite a large amount and made inquiries through commercial suppliers for a two pack mix, but eventually decided against it because of the price. I dont know if the single pack stuff is closed cell or not as it only came in aerosol cans and the quantity I wanted was too big for that.
DepSol
Well-Known Member
Make sure its the one used by boatbuiders s the other is no good.
Dom
Dom
I just want my boat back in the water ;-(
Dom
Dom
I just want my boat back in the water ;-(
dick_james
Well-Known Member
Be careful
Make sure you leave space for excess foam to escape. It can exert quite a high pressure. The two part mix is the stuff to use I believe.
Make sure you leave space for excess foam to escape. It can exert quite a high pressure. The two part mix is the stuff to use I believe.
terryw
Well-Known Member
Be very careful if using the aerosol foams because most are not fire retardant.
Some years ago, when I was in Civil Engineering, I conducted some basic tests on these foams. It consisted of spraying a small amount to form a pryamid shape, letting it cure, and applying a naked flame. Most just went up in smoke at an alarming rate, and some just melted locally and extinguished the flame. If you intend using an aerosol (or any other type) it may be prudent to test it first.
Some years ago, when I was in Civil Engineering, I conducted some basic tests on these foams. It consisted of spraying a small amount to form a pryamid shape, letting it cure, and applying a naked flame. Most just went up in smoke at an alarming rate, and some just melted locally and extinguished the flame. If you intend using an aerosol (or any other type) it may be prudent to test it first.
oldharry
Well-Known Member
Whatever type you use it absolutely MUST be closed cell foam, otherwise it acts like a huge sponge and sucks in any water, which you can not then get rid of.
The builders aerosol type foams are nearly always open cell, and wordse than useless on a boat if the water gets anywhere near it!
The builders aerosol type foams are nearly always open cell, and wordse than useless on a boat if the water gets anywhere near it!
vyv_cox
Well-Known Member
Even the two-pack type sold by GRP supplies people, Strand, Glasplies, etc, are not 100% closed cell. If left immersed in water for some time they will become waterlogged and sink. If you allow unrestricted expansion of this stuff, then cut it open, you will find very large voids inside. Restricting the expansion will increase the percentage of closed cells, but careful mixing and design of the vents is required.
I have seen it suggested that epoxy resin plus micro-balloons works well for this job. No experience myself.
I have seen it suggested that epoxy resin plus micro-balloons works well for this job. No experience myself.
oldsaltoz
Well-Known Member
G’day Johnboy.
Have you considered using “Q-Cells” or Micro-Balloons, they are closed cell and are not effected by water; not expanding though so you may have to remove a part of the rudder an re glass it, not a major project but it will not need doing again ever.
Avagoodweekend Old Salt Oz
Have you considered using “Q-Cells” or Micro-Balloons, they are closed cell and are not effected by water; not expanding though so you may have to remove a part of the rudder an re glass it, not a major project but it will not need doing again ever.
Avagoodweekend Old Salt Oz
ccscott49
Well-Known Member
Micro ballons and epoxy, works very well, but if it is a big area you need to fill, will be expensive and very heavy. Clsoed cell foam is the stuff. but there is some bigger ball type stuff you could use and epoxy, I can't remember the name of the balls.