Foaming or non-foaming caulk?

I've been researching caulk here in China, and it seems most are the foaming type like these: http://b2b.hc360.com/supplyself/38084849.html http://b2b.hc360.com/supplyself/40981714.html http://b2b.hc360.com/supplyself/2385645.html I was told they expand to something like 50 times its original volume, and then you cut off the excess once it's done expanding. So are these foaming caulks ok? (In their description they say these products are great for sound isolation.) Should the caulks be non-foaming?

No no! That's not caulk, that's PUR. Forget about that immediately. Caulk is also known as "kit" A caulk tube looks like this:

note: this is INCL a caulk-gun (the device to apply the kit with)

Ro wrote:

No no! That's not caulk, that's PUR. Forget about that immediately. Caulk is also known as "kit" A caulk tube looks like this:

note: this is INCL a caulk-gun (the device to apply the kit with)

What are the practical differences in what they can accomplish?

What are the practical differences in what they can accomplish?

I believe there are several, actually. I am pretty sure that the kind of foam that you are writing about will expand and then become quite rigid/hard. I am not 100% certain but I think the characteristics of such a product has few typical implementations in acoustical sealing. I would not presume to know the facts here but one way to explain the difference between kit and foam would be to say that they have different ways of adding to their environment. I am sure there are tons of differences... but one very basic difference could be that foam might have a somewhat lower resolution than kit, when it comes to creating "air-tight" seals. Another would be to say that the hardened foam might in some cases serve as a flanking path whilst the softer characteristics of kit may provide isolation "only". I'm no expert. Just some thoughts. /Gash

It's like shampoo vs toothpaste. both used for cleaning/health but total different purposes. Once you see it you'll know it. Forget about foam/pur. Focus on caulk (aka kit) Another different product which can be confusing is Greenglue. It's not *real* glue and it's not caulk either. But great for acoustic purposes. Read the forum to get up-dated with semantics and products. good luck!

It's like shampoo vs toothpaste.

Thank you Ro. Even though it is not quite what I had in mind when explaining, I still think that your explanation is a much simpler analogy. :D /Gash

The problem right now is, I cannot seem to find any acoustical sound sealant/caulk/kit in China. They only have the foam type as far as I can tell, or just normal kit not specified for acoustic purposes. So if I had to pick between a foaming caulk that sayd it can do sound isolation, and a regular kit (not specified for acoustic purpose), which should I pick? Of course, I can try to order the real deal outside of China, but it's going to be complicated I think with China's customs.

The links you provided typically shows PUR appliances. the fact that the website says "good for acoustics" or whatever is nonsense. (marketing talk) Go to your hardware dealer and ask for Acrylic or Silicon caulk/kit. Check the specs on the tubes or do some research on the products website. Kit should not shrink too much (<5% to start with), stays flexible and has some decent mass (colored kit has more mass than transparent kit) Silicon is more expensive but does shrink less. Look at the picture I've shown, print it if you will and shop around. Ask your hardware-dealer (show'm the picture) Too bad I can't read chinese or I'd do a google search for ye...

Silicon is definitely a lot more expensive (2x or 3x) than latex, at least where I live, and I believe much more difficult to clean up. and it might be smelly too. i don't think you want to use it without good ventilation. Brian Raavnas recommends latex as a cheap alternative to "true" acoustic caulk ... try to get big (about 1-liter size) tubes, bigger is easier to work with so you don't constantly have to change tubes. Brian's "cheap tips:" http://forum.studiotips.com/viewtopic.php?t=2837 Don't get the foam stuff. Even if it did work for acoustic sealing it isn't good because it expands A LOT and you won't be able to get a controlled bead laid into the gap, it will be ridiculous lumpy and out of control. Also it is very low-mass and I don't think it will stop sound as good as caulk. Also use foam backing rod. It will make the caulk seal last much longer, and it will also save you from using a lot of caulk.

Thanks! That really helps. I'll go for the alternatives if I can't find the good acoustical stuff.

Lunatique wrote:

I've been researching caulk here in China, and it seems most are the foaming type like these: http://b2b.hc360.com/supplyself/38084849.html http://b2b.hc360.com/supplyself/40981714.html http://b2b.hc360.com/supplyself/2385645.html I was told they expand to something like 50 times its original volume, and then you cut off the excess once it's done expanding. So are these foaming caulks ok? (In their description they say these products are great for sound isolation.) Should the caulks be non-foaming?

Sister , that isn't caulk. And I cannot even read mandarin and I can tell you, that isn't caulk :)

shove it X, we told here already. :twisted:

funny, I'm a regular reader (few posts) on RO (gheh), gearsluts and a few other audio related forums. But I'm not near as active as I am on this one. This is where, imho, it happens when talking about designing and building studios. The best resource if you'd ask me. I rarely check other studio builds/questions on all the other forums... oh well.. :jammin:

lol oh well.. :jammin:[/quote]