is it OK to use vaseline to dry fit ABS

what is a "proper interference fit"

the instructions say not to enter the pipe more than 1/3--2/3 inside the coupling. is that just for the dry fit or the final glue as well? i've been pushing them in as far as they go when i glue.

I think you would need to clean the pipe ends and fitting interior with something like mineral spirits to get the grease off. Never tried it, so this is just a guess.

You can but your creating way more work than you need. No one I know would ever do that. And if you don't get all of it off you are asking for a leak not to mention that I have no idea if it will affect the pipe at all. I doubt it, but I don't know.

Petroleum products, including Vaseline, usually damage plastics.

Dont do that. You just need to develop the "eye" to make your measurements to account for the wet penetration depth.

In the first place, the fit is what is called an "interference" fit. It is not just friction; the pieces actually are of such a size that absent the SOLVENT cement, they do not go to full depth. Greasing up and forcing the fit could damage the parts so that even IF you could clean them up correctly, they might not glue up properly.

The idea is that the solvent cement slightly dissolves the plastic on each piece. Then when you force them together, its like squishing together 2 pieces of soft chocolate. They become one solid plastic part.

It doesn't make any sense to dry fit plastic fittings.

You just slop on the glue, and go for it.

Well what do you know! I use the same high tech methods as Terry. "Slop and Go"

"Slop and Go" is what we do for lunch

After you glue up a few fittings, you will develop a sense for how far in they go. I use as much force as I can muster when I glue fittings. Andy don't bother with vaseline. I expect that it is going to be tough to clean and will interfere with the cement.

Some places require that you use a primer (the dreaded purple primer) before the solvent. This is a mixture of Methyl Ethyl Ketone and mostly Acetone (nail polish remover). It cleans and 'melts' the plastic.

You can make a poor man's primer with 90% acetone and 10% MEK, and you won't get that great purple dye all over everything. However, if code requires it, and yr getting yr stuff inspected, they'll have no way of verifying that you actually used a primer.

You'll know yr primed good enough if you can scratch a mm or so of soft plastic off the prepped end and fitting.

I believe petroleum jelly will not dissolve plastic, but it will coat it so yr solvent and primer cannot adequately penetrate. That's why they smear it on babies' butts so they won't get diaper rash!

- p