Glue suggestion?

[Dan Daniel]

I am looking for a glue or caulk material that is between an epoxy like JB Weld and RTV gasket material. This is for a film chamber wall installed in a camera. It is subject to pressure from the film spools being pulled, so an RTV seems a little too flexible. JB Weld seems too hard and brittle, and not good for any sort of fillet work, not just internal adhesion.

Anyone know of an adhesive that is stiffer than RTV gasket material? Hard to describe but more flexible than off-the-shelf epoxy like JB Weld? An epoxy known for some flex? Maybe a urethane?? And black preferably!

Thanks.

 

[DREW WILEY]

Oh my, you are looking for something maybe too exotic too exist, at least for your application. There are many many kinds of epoxies; many are reinforced and not brittle at all. Urethane sealants are generally designed to be just as flexible as RTV sealants. Hard urethanes aren't going to work well in this application. If I were in your shoes, I'd start looking for an aerospace supplier. There used to be one around here in Silicon Valley I once dealt with for my own special sealant needs; but those connections have dried up - they generally didn't sell to the public anyway. I had an inside track because we had our own military sales division.

Take a look at McMaster's selection - they'll sell to anyone in small volume if they have it. That's another source that I've often relied on.

 

[BrianShaw]

Perhaps Flex Paste?

Flex Paste® | The Seal You Trust When It Matters Most

Super thick rubberized paste that fills gaps and seals cracks, creating a barrier you can count on for repairs inside or out. Free shipping on orders $30+

flexsealproducts.com

 

[DREW WILEY]

That "Flex Paste" is worthless. It needs a sanded surface, has to be glopped on thick like roof patch, and will likely peel anyway.

What has just come back to my memory is black Kampel SeamFill, used for filling and disguising thin Formica seams and small dings. Proper use requires a little practice; but the product is readily available from multiple sources, including Amazon. I always kept sheets of black Formica or Wilsonart in my shop for darkroom applications.

 

[Besk]

I just used some Loctite Flexible Adhesive to repair the leather on some shoes. Maybe a little too flexible for your your use but I was impressed. Cheap from Walmart.

 

[BrianShaw]

That "Flex Paste" is worthless. It needs a sanded surface, has to be glopped on thick like roof patch, and will likely peel anyway.

Just correcting one piece of incorrect information (the rest I'll leave to Dan to research and/or try whatever he thinks may work.

Flex Paste does not require a sanded surface for application.

In my own work, I've personally used this product and find that thin coats work well too (not for roofing but for similar applications as Dan describes). Peeling is nothing I've experienced in my own work. Your speculation is possible, I'm sure, but it sounds like you aren't completely sure of your statements. I also had access to a government research lab that used it for prototype developments, which gave me the incentive to use it in my own efforts. The biggest downside I've found is that it is solvent-based so cleanup requires a solvent. Oh, and it really can't be thinned with solvent, which might be a bit of a limitation in extremely fine applications.

I've also used a similar product to the formica seam filler. It is tricky to use but seems to work too. Some of those silicone products are sanded, like grout... something to be aware of when researching them for non-standard applications.