Un-stick PVC Joint that got a little primer in it? (Kerdi Drain)

I'm working on a Schluter Kerdi shower, and installed the riser for the kerdi drain yesterday. In order to ensure the riser was plumb, I had the kerdi drain dry fit to the top of it, with the intent to pull off the drain once the riser was set. This morning I find that I CANNOT pull the kerdi drain off the riser . I have to assume I got some primer in the joint. Any suggestions on how I might be able to separate the drain at this point, without ruining it?

How did you get primer into the joint if you dry fit it?

Whew, I got it off.

Obviously I was too liberal with the primer, and some ran down while I was handling the assembly:

Yeah I was curious because the drain would be on top and the trap on the bottom. Primer doesn't run up.....it runs down. Use a rag to wipe up excess primer and solvent.

Your biggest mistake was dry fitting. PVC has what is called and interference fit which means when you dry fit it together, it wedges in and is very difficult to remove. The solvent liquifies the surfaces of the pipe and fitting so the pipe will slide into the fitting and bottom out. Primer and PVC cement do not stick the pipe and fitting, the joint is chemically welded.

Although what you said is typically true, the kerdi drain will allow a full dry fit without issue. It still comes apart unless you are sloppy with the primer like I was

I was surprised at that, but noticed that the Kerdi drains I've played with have what seems like very little taper to their socket, and you can bottom it out on a riser and still get it off without contortions as long as it is dry. The primer has some solvent in it, but not as much as the cement, so getting any of it on a joint will make things sticky.

FWIW, the primer and cement will easily eat a hole in their foam tray or curb material...I can tell you that from experience! Not generally a problem as a bit of thinset will fill it in, but don't spill a lot!