Over here in germany we use "Schmand-Weg" bought from amazon. this stuff Just pour 2 teespoons of it into 1 litre of hot water and let your pipe sit in it for about 5...10 minutes depending..and your pipe is as clean as it used to be when you got it.
I take a heated 5/16 brass rod just like a rifle cleaning rod and ram the rod through my pipe . All my wooden pipes are aluminum , brass or glass tubing lined. Pipe in this picture has a 1/2 aluminum tubing inside it.
boil water soak first to remove large stuff. then rubbing alcohol with salt & dry rice. plug all the holes and shake through an entire Led Zeppelin song. repeat as needed. worked since 1992 for me
You can simply soak the pipe in water if it is glass. My assumption is the water weakens the resin's bond and the natural tendencies of oil in water. But I don't know, and this takes about a day to actually clean everything. I'm a fan of using 95%+ grain alcohol, I use Everclear. This is how I clean grinders, I just use whatever works to clean my pipes, generally a bobby pin. I don't care for them to be spotless, only that they smoke well. Plus a coat of resin in the bowl seems to make them burn well and not need to be sparked as often. I use Everclear because is food safe and when cleaning grinders, you can reduce it down and dab what's left, or activate it before hand and drink it. I mean, you can do that with resin also, but... why would you lol
Water isn't so good unless its boiling, other then that water will not touch resin. Denatured alcohol I think is the best for a glass pipe.
Course sea salt and alcohol have always worked on glass and metals - Just put some salt in then add some alcohol and let sit for a few minutes than shake and swirl till clean - may take a few times to get it completely clean. Plastics I use citrus hand cleaner with pumice like gojo and a scrubbing wand of some sort
Finger nail polish remover is my go to. Really quick and cleans it better than anything else I've used. Pour enough to cover your pipe into a zip log back, place your pipe inside and shake that shit for about 5 minutes. Remove it, run clean water and a bit of soap through the pipe (to remove the residual acetone) , let it dry and then smoke up.