I've been having trouble with fittings coming loose at my stepson's place. I noticed today that my primer [not a new can] takes a long time to dry [10-15 minutes] I always thought it dried almost instantly although I've never paid a lot of attention to it. Could tacking primer cause the glue not to adhere/dry properly?

 

I have never used primer so can't help you there but a guess is maybe the old primer is causing the problem. Have you tried without using primer?

 

I never used to use primer and never had any issues but after hearing about it being needed from so many people/plumbers I started using it about 5 yrs ago. When I went back to try again this morning I paid extra attention to everything and that's when I noticed the primer was slow drying. IF it fails again - I'll try it without primer.

 

You need to use the primer Mark. Are you using the purple stuff or the clear? I know inspectors used to just look for the purple to ensure primer was used. Dunno what they do if clear was used. Primer, IIRC, is mostly acetone and is a thin liquid...it should dry by the time you get the lid on the can and open the glue. If it doesn't, the acetone is all evaporated out.

The "hot" glues like "rain or shine" or "Blue Lava" don't require glue. The regular or all-purpose stuff does...per the manufacturers. https://www.plumbingsupply.com/the-g...er-debate.html

 

I think I'm using the blue lava, any way it's blue glue and dries in 30 minutes instead of 2hrs. Are you saying no primer is needed with the blue glue?

Would there be any sense in adding acetone to the primer? It's the purple primer, everything came from Lowes.

 

Nope...no primer needed with the Blue Lava hot glue (if local code allows)....but why are you using that? It sets quickly according to the maker, but regular stuff sets in just a few minutes also in warmer temps... It shouldn't take 2 hrs unless you are working in sub-freezing temps. Of course actual "cure" times for max pressure rating will be longer depending on temp and pipe size.

I've never had the need to use the hot or medium glues...but I've never had a joint fail as long as I did the "insert, twist, hold" thing. 10-15 sec later I'm ready to move on.

 

When PVC piping was first introduced there was no such thing as primer. The instructions DID state it was necessary to use sandpaper on the pipe and fittings to cut through the hard shell in order that the solvent cement would properly soften and bond to the plastic. So many people ignored this step that the primer was developed to soften the hard shell prior to using the solvent cement. Even then people would skip this most important step and that is why the purple was added to the primer, to show the inspector that the primer had been used.

As I recall the instructions now state to slather on the primer and while it is still wet to slather on the cement.

 

I bought the blue glue when I was replacing busted pipes from freezing last month .... and still had some left.
As far as cure time before full water pressure I'm going by what it says on the label - 2 hrs for the regular cement and 30 minutes for the blue stuff.

I haven't got a call saying it's come apart/leaking so as far as I know, the 3rd time was the charm.

 

Absolutely use primer and glue immediately after applying primer, always give that 1/4 turn wen seating the joint to ensure consistent joint.

 

Looking at the article that guyguy posted, you're better off not using primer in most cases.

https://www.plumbingsupply.com/the-g...er-debate.html

I spilled a can of primer in my van once. It took forever to get rid of the stink.

 

While I normally do that, there is always that last joint that you can only slip on as there is no way to turn it.
Since it seems that primer isn't really needed I believe I'll go back to not using it.
Thankfully the last time my stepson called it was just to talk to his mama