Drysuit neck gasket replacement... fail!

First, I cut off the old neck gasket. Then I cut a couple of rings from 1/4" starboard plastic (7" ID and 10" OD) to use to clamp the new gasket in place...

Then I lightly sanded, spread the glue (Aquaseal), clamped it together, and waited more than a day. It easily peeled apart, very easily coming off the new gasket, and not sticking well to the old gasket material either...

Any ideas why this might have failed? I'm baffled.

I am not too sure why it came apart maybe the glue is bad or not enough time to dry? I watched some YouTube’s on kokatat neck gasket replacement and was able to do it (also least handy person ever) Although if you see my neck gasket now there is a ton of glue on it. I didn’t have a lot of tools to do it. I used a kitchen bowl and let it dry for a while and just used some heavy stuff to make sure it stayed down (no clamps).

Some use conditioners on wetsuits, and gaskets. Have you ever used them in the affected area?

Do you need an adhesive promoter?

I've not used any conditioner on the drysuit. No promoter, but I think the only thing that I've seen used with Aquaseal just speeds it up, as opposed to making it stick better. Maybe the glue was bad, but it stuck tenaciously to Gore-Tex fabric, where some squeezed out.

I decided to try the approach in the video below, where he removes the entire neck gasket, then glues the new gasket to the fabric. I was able to get the remnant of the neck gasket off without too much trouble (hopefully, no delamination, as it did seem to come apart in one small area). The dried Aquaseal that I'd put on was another story--major PITA. I'm 100% confident Aquseal will stick to the fabric, so it's just a question of whether it'll stick to new gasket. I'll do a small test beforehand...

A couple more pictures. Once I get the glue, I'll give it (another) try...

I got a new tube of Aquaseal, and glued together a couple of scraps of rubber that I trimmed off of my new neck gasket. I scuff sanded, smeared on some glue, let the glue get tacky, and I then clamped the pieces together, as recommended in various videos. After 36 hours, it easily peeled apart.

I'm baffled. I'll try another experiment with the old neck gasket, just to see if it might be an issue wrt the new gasket. If that also fails, I'm out of ideas...

Here is my latest attempt. I think I did everything right--not sure if it si supposed to be this easy to peel apart...

It looks like nobody is following this anymore, but just for my own info, as by the time I need to replace this again, I will have forgotten everything.

I've discovered that since 2009, Kokatat has not used Aquaseal to attach the latex neck gasket to their drysuits, as mentioned, for example, here:

https://www.kayakacademy.com/products/gasket-replacement-service-kokatat-neck?variant=43398306627828

Instead, they use an unspecified "heat activated adhesive system". Based on my experiments, there is no way that I'd trust Aquaseal to have sufficient holding power in this application.

I'm hoping that I can figure out what this mysterious "heat activated adhesive system" is and, if so, I'll try it myself. If not, I might be forced to send it in to get a new gasket properly attached...

I'd look at bike patch glue - many bike tubes are latex.  Contact cement might also work.

I have been following but I’m baffled as well. The Aquaseal comes with the gasket repair kits so you would think it would be fine to use. On my older suit I replaced the wrist gaskets twice using Aquaseal without any issues.

I have been following but I’m baffled as well. The Aquaseal comes with the gasket repair kits so you would think it would be fine to use. On my older suit I replaced the wrist gaskets twice using Aquaseal without any issues.

Maybe it is a different formulation of Aquaseal or maybe a different variation of rubber for the gaskets?  Adhesives are strange - as are rubbers and plastics.

I wish there was a good adhesive for HDPE... The only options there are pretty expensive, require extensive prep or heat, and seemingly being some pretty awful fumes with them.

Slightly off topic - can you replace the latex gaskets on older suits with neoprene? I know it wouldn't be quite as waterproof, but it would have to be a whole lot more comfortable. 

Slightly off topic - can you replace the latex gaskets on older suits with neoprene? I know it wouldn't be quite as waterproof, but it would have to be a whole lot more comfortable.

That's actually a great question, and I did spend some time searching to see if I could get ahold of a neoprene neck gasket. So far, no luck, but if I can find one, I'm confdent that I can sew it on and use seam tape to waterproof it. I also own a Kokatat semi-drysuit, and I think that I can do a good approximation of the way that the neoprene neck gasket is attached on that one. I'm sure that would void my warranty, but it would certainly be more comfortable.

Another crazy idea that I had was to buy a silicone neck gasket, and then sew it on (apparently, gluing is not an option), and use seam tape and aquaseal to waterproof the connection. I think it would work, and by all accounts, silicone neck gaskets are way more comfortable. Tempting...