[seeded]

Back when I smoked bongs I would use methylated spirits and rice to clean my glass and once clean I'd wash it again with my dishes to get the last of the taste and smells out.

Now that I vape I have a jar of isopropyl alcohol in my fridge that I store all my dirty glass and screens in for a few days. I collect them in a strainer above another jar which then gets put back in the fridge and the bits are cleaned again to remove any lingering tastes or smells. Every few months I change the iso and get a surprisingly large mixture of low quality oil for free which is a nice reward for lazily cleaning my gear.

[St. Phatty]

All my pipe parts (that get dirty) are metal

so I clean them with a drill, except

the 6 inch long piece ...

I clean that with a piece of 1/4 inch all-thread.

[Mukind]

I soak my sliders/downstems in simple green and just keep them in rotation. If i used smaller rigs I'd probably soak those too

Tube gets iso/kosher salt

Acetone works best but is more combustible, it's what you would use in a chem lab to clean glass. Will break down organic and non organic material, so just about 100% chance enough of it will rip off labels.

If iso/kosher salt isn't doing the job the next step up is acetone. Just do it in a well ventilated area if your'e going to be making a mess of it

Heat helps too

If acetone isn't doing the trick, you'll need more friction. Got to ram a metal wire brush or a piece of steel wool to scrape it off. Or just spend a lot of time with some granules in the acetone wearing away at the grime.

I restored my first bong that was used in days where I didn't have access to a sink very often. It's now good as new. But I put probably a dozen man hours into getting it that way. Wasn't worth it but this knowledge comes from first hand experience for that reason.

And break cleaner works, you will meat gear heads who recommend it, but not well enough to use it over acetone or alcohol

You could use spirits, but that isn't very cost effective. Simple Green and Acetone are about 12 a gallon. Iso is about the same from wallmart

Edit - use simple green to soak because if you forget to cover your container half of it won't evaporate at all relative to alchohol or acetone