Sikaflex-221 Polyurethane Adhesive/Sealant 10.1 fl. oz. Cartridge, Black

Initial impressions are that this is going to hold up better than silicone. Time will tell. I like the fact that it will cure even at very low temperatures, though it does cure more slowly. For storage of the unused amount, wrap the tip of the cartridge with cellophane and store the cartridge in the fridge. Keeps for months without hardening!Note: this urethane clings to your skin like nothing else -- it wipes off easy and doesn't feel sticky, but your fingers will be black for a week. Guaranteed. Nothing scrubs it off except time.

I don't know if this is the way suppose to be but I almost broke my hands squeezing this sealant out with a caulk gun! Very very hard - I was under impression that this suppose to be more in liquid form that will cure into a rubber seal. Not sure I will buy this again.

I used this to glue a fiberglass high top to my van. I currently use no reinforcement in any way, this glue is holding it one with a thick initial bead and about a 1" wide backfill bead on the inside. 2k miles with no issues or cracks, great stuff!Do not get this on anything you care about, it has incredible bonding properties and is very hard to remove from anything that isn't smooth. I layed a relatively thick bead and it outgassed for about 2 weeks where it was hard to stay inside the van for long. After that the smell persisted but without the burning eyes xx. 1 month and I hardly smell it at all, just smells like a boat now.

1 star because when using sealants the user often does not realized till its too late. In this case it was impossible to extract and I had to delay my project. I took a look and sure enough expired almost a year to the day. In other cases it might have caused a failure down the road making matters much worse, causing de-bonding of materials or water intrusion. Make sure the sealants and adhesives you sell are up to date!.Update: return request prompted seller to send out a fresh tube. Which expires in a month. Thanks a lot. If I could give another 1 star I would. Don’t sell old crap on Amazon.

A little gummy to work with but created an excellent and strong seal. I used this to help secure solar panels on the roof of my camper van. Tip: have a scrap piece of cardboard or paper around for "cleaning up the tip" every so often.

Made a new motor mount for my 1985 Toyota MR2 (AW11) with this stuff. All I had to do was cut out the old rubber and burn the remnants off with a torch, then tape up the one side, place the metal core in the middle, and pour this out of a caulk gun into the empty space. It was still soft after 24 hours, so I let it cure for a week. It got firmer so I put it on my car. It's held up very well as a transmission mount, so I used it to fill in the extra gaps on my other motor mounts to stiffen them up a bit. So far it's worked out great, and I feel much better throttle response thanks to the engine and transmission not tilting around.I'd use this product again for all sorts of purposes where I need something that adheres and is soft enough for flexibility but tough enough not to crack or break. Overall I'm very satisfied with Sikaflex 221!

I tried to find a solvent that could be used to cleanup the Sikaflex 221 caulk but all that is mentioned in the data sheets and on the company's website is their 208 Remover product. If I was going to use this product only then I would pay the $60 for a bottle of the 208 Remover but for my projects I have opted to use other products where I can use conventional solvents for cleanup.It is exceedingly toxic and the MDS talks about needing to get immediate medical attention if it comes into contact with skin or the fumes are inhaled. Many compounds need to be used with care but the Sikaflex 221 takes it to a whole other level. I decided to use the Titebond MP Sealant instead which cleans up with household isopropyl alcohol.

Works well on my Airstream