I tried to follow the instructions for sealing bulkhead penetrators with the Thixotropic 80A potting compound, but it seems I must have messed something up. The platic has cured quite soft, like a gummy bear.
What did I do wrong?
I used an epoxy squeeze gun and mix tip, and I squeezed a little out first, so I believe the mix is good (but I could be wrong).
I know winters in California are epoxy nemesis 100% humidity and 10C. Should I do this with the heater on or wait until warmer weather? Will they ever finish curing if I put them in the oven?
Edit: move to the correct topic categroy. Also a little more about my application
I am connecting some control lines from the control pod to the battery pod with a spare length of the yellow tether cable. The epoxy cured soft, and also it fails vacuum. Replacing my cable penetrator with a blank gets it to pass vacuum so I am sure it is the cable penetrator.
It passes vacuum and appears to be the same stuff as is sold on the webstore. My technique was the same as the video for potting the power cable, though I did add some teflon tape around the wire on the bottom so resin doesn’t get all over the floor or on the threads. I may not have gotten enough resin below the outer jacket to seal around the individual conductors.
Does the cable itself leak air in between the wires? Should I have done a ‘second-op’ of turning the penetrator upside down and potting the back? Or is my technique flawed and I should practice a few more times how its done in the video? Is the technique for potting the yellow tether cable the same as for potting the power cable?
Most of the penetrators we pot are oven cured, and that speeds up the process a lot, taking only a few hours. However, we do cure all our potted tethers in air in a room that is about ~15-20°C right now. Once they cure undisturbed for 4 days, they are solid enough to handle without damage, but they do continue to cure a bit more while they sit in inventory and are shipped to customers. 10°C is quite low and will increase the cure time a lot, the instructions on the cartridge are a general guideline assuming comfortable room temperature.
Four days at room temperature (~21°C) should be a comfortable minimum, and I would only suspect that something is wrong if the potting is still gummy after 6-7 days or so. You should definitely at least turn a heater on if the temperature is significantly below this baseline. Putting them in the oven now should help, but in varying the curing temperature too much during this process can have adverse effects in some of our limited experience. We always commit to either full oven cure or full ambient cure, and don’t normally mix them.
The potting technique shown in the video and instructive tutorial is the correct method that we recommend and have been using exclusively in production for almost a year, for both tethers and thruster penetrators. Potting the back is unnecessary and will not increase seal performance. The only goal is to seal the cable jacket, as the individual wires are not sealed, and air/water can leak between the wires and within the wires between the individual wire stands. This is why it is important to ensure the cable jacket is not cut in any place, otherwise a leak will result.
I also have the same problem. The epoxy is not setting and still gummy after almost two weeks in a room temperature (~21°C). I’d like to try the oven. I’d like to know if it is safe to reuse an oven for food. Is the epoxy poisonous when heated?
I would not generally bake any non-food or food safe items in a kitchen oven. It does not significantly off-gas, but the epoxy itself is toxic if consumed. For more information, please see the MSDS information in the technical details.