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Easy spray/liquid *open cell* foam? Answered

Hi all - new here  :)  I was trying to think of where I could ask this and I immediately thought of instructables.  Does anyone have any ideas where I could find a spray or liquid *open cell* foam?  It's easy to find cans of spray closed-cell foam these days, but I've never seen one for open cell foam.  I've done a lot of searching, and the only open foam cell solutions I find tend to be giant expensive things for insulating houses in bulk, nothing for small scale applications.  I'm looking to fill a bundle of relatively fine tubes (diameter TBD), which I want to act as a sponge on the inside, resisting allowing the liquid inside to drain out while still allowing for gas migration.  Hence closed cell is not an option.  Polyurethane is probably fine, although other materials may well be fine as well.

Any ideas?


depending on length and dia, you might sharpen the end of the tube and use it to cut a plug from foam.

Hey, that's kind of clever, at least for the small scale. However, there's one problem that jumps out.... unlike closed cell foam, open cell foam is very flexible. It's not going to cut into a plug very easily, and even if it did, it's unlikely that it'd spring back up the tube.

Maybe if I froze it in liquid nitrogen first.... hmm, I'm probably overthinking this....

yeah. Try the easiest thing first. If it don't work, ya didn't invest much effort.

Using tubing to cut a plug (or a hole) is somethin I've done on the 1/2 to 3 inch scale with good success. U wanna grind somethin like a knife edge on the end o th tube, then rotate tube into foam (or rubber, whatever

Well, trying it would mean acquiring a large block of open cell foam, for something I think is pretty unlikely to work. But I could try. I picked up the varying sizes of tube today at least.

sometimes a bigbox store will sell damaged sheetgoods at deep discount. Is insulation yer option? What about floral foam?

Foam plastic insulation is generally either closed cell, or soft and flexible and thus not something that could be readily stabbed into a tube. Rock wool, I doubt that would go up a tube either. Any other types of insulation you're thinking of?

Floral foam - being both open cell and yet firm and thus "stabbable" - is a neat idea! Or was until I looked what it's made of :( It's phenolic. The liquid in question might... um... explode in contact with it if shocked ;) Foams like polyurethane have some contact sensitivity, but are usually considered fine for short-term usage, which is my case.

I may just have to gel it with fumed silica or something, or rely on backpressure when the base is open to keep the liquid in.

other options: those bubble rock things on the end of a fishbowl aerator tube. It's porous lava, iirc. Or can concrete be made porous with the addition of somethin

The technique with a sharpened tube is not to stab, but to rotate the tube as it is pressed into the material. I've done this with foam rubber, tennis balls, semi-hard foam, etc. Consider how you cut a tomato with a knife edge. you don't just press the blade straight down. you saw a bit.

At this point, I'd say play with lotsa different materials until somethin works.

...and if there's a chance of 2 materials spontaneously igniting, try it small first. and outdoors. and _UnContained_.

Did you consider copper or stainless steel pot cleaners?
I use them for my still and it should be possible to get them through small diameter pipes if you rip the stuff into single strands first.

Do you mean, like steel wool? That doesn't retain liquid. And I don't know whether the diameter would be conducive yet (might, might not).

That said, it makes me wonder if pipe *cleaners* might work.....

(in case you're curious, the application is "rocketry", hence the chemical compatibility issues)

can I ask about more details about what this whatchhoozit does? Or would that violate proprietary info?