Clear sticky residue in female threads


We got our printer a few weeks ago and have been printing with grey resin. I am printing parts with male and female threads that fit. At first I was very happy with how both male and female threaded parts turned out, I was able to screw the parts together nicely. After about 750mL worth of printing, I noticed a clear sticky residue inside female threads. This was after 10 min of washing in IPA and 30 min cure. This residue make it very difficult to screw the parts together. I thought it might need more curing because the UV light might have trouble reaching the female threads deep in my part. I tried curing for an additional 30 min, placing the part at an angle to try to get the light inside, but this didn’t seem to work.

Do I need to figure out a way to get the UV light down in the threaded hole or is the clear sticky residue caused by something else since I wasn’t having this problem at first?

Attached is a picture of the working part (top) and the sticky part (bottom).

I think the key in this situation is your baths- if the residue from printing is still sticking to your threads when it goes to cure, it will just make the threads more gunked up, which is what I think you’re literally running in to.

You might only be seeing it now because of the contamination of the IPA with resin, or a change in print orientation, or similar factor.

I have found that physical removal is sometimes needed, even with high% IPA. Maybe try running a small, soft bristle brush across the threads when it’s in bath#2?

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I use both a stiff brush on all parts with details to help remove any residue from the IPA rinse… but after the second rinse I use a high pressure airgun to blow the IPA off and out of details.

Post cure the part while it’s in water to keep the oxygen from hitting it. The sticky should go away.

100% agree with @sigmazero, especially with Standard resins you shouldnt’ have much stickiness even before post-curing, so if your part is sticky it’s probably not clean enough. If you are using the standard finishing kit, depending on the ammount of resin left on your parts before cleaning it’s possible that the IPA is poluted enough that a 10min wash doesn’t suffice. I’d try 10min in the first bath, then 10 in the second, while agitating the parts often.

I do as well, especially when there are intricate voids in the part.

Thanks everyone! The cleaning tip worked. After the normal wash in IPA bath, I used fresh 100% IPA and a paper towel to clean the threads. Soaked the paper towel in IPA, then stuffed it in the hole, and twisted it counter clockwise a while. That worked great!

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Yes, it helps to do a final rinse in clean IPA after you’ve finished soaking

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