Reason for using primer on PVC joints

[Wrex]

I personally think that the cleaner is a waste.

I just use the purple primer then the cement.

Of course before applying the primer I make sure that the pipes and fittings are clean and dry with no grit dust or dirt on them which could compromise any joint.

 

[Verdeboy]

The "cleaner" and the "primer" are EXACTLY the same, except for the purple die, which is added to the "primer" so inspectors can tell for sure it has been primed. If you use both cleaner and primer, it might be redundant, but you are helping the economy. LOL

This thread has now gone around and made a complete circle. WOOT!!

 

[Sponsor]

 

[Wrex]

The "cleaner" and the "primer" are EXACTLY the same, except for the purple die, which is added to the "primer" so inspectors can tell for sure it has been primed.

Ah ok thats pretty wasteful marketing 2 products that do the same thing.

If its purple for inspectors to check it then why sell the other stuff without the dye?

I guess it's also so the inspectors can also tell WHO primed them "see purple hands" .

 

[adb]

The "cleaner" and the "primer" are EXACTLY the same,

The cleaner and the primer are not exactly the same, chemically or in function.

The MSDS for Oatey's cleaner lists the ingredients as
60-100% MEK (methyl ethyl ketone), 15-40% acetone

MSDS for primer lists the ingredients as
60%-100 acetone, 0-20% MEK, 0-20% tetrahydrofuran, 3-10% cyclohexane

The cleaner is used to clean up grimy pipe. It could be used solo before the installation of a compression fitting, or as an optional initial step before priming. I would use it for the latter before priming a pipe covered in grease, paint, or other similar grime, but it would be superfluous on new pipe. The general purpose of this extra step is to ensure the primer is able to properly soften the pipe's surface to accept the cement. If the primer brush is just wiping off paint, there is some likelihood that the pipe will not get primed properly and the joint could fail.

Cleaner aside, the primer is not optional, even on new pipe. Its role is to soften the outer layer of pipe so the cement can solvent-weld the joint, instead of merely gluing it together.

Cementing PVC without priming it first is not much different from gluing it together with cyanoacrylate (superglue). You could do the same with copper and have a joint you couldn't pull apart by hand, but without fusing the materials the joint won't last under years of thermal expansion/contraction, pressure, vibration, etc. Hence the volume of stories earlier in this thread from plumbers repairing earlier unprimed work.

If it's worth doing, it's worth doing right.

EDIT: Cleaner is also useful for ABS. As someone noted earlier in this thread, you do not prime ABS joints because the plastic layer around the pipe's core is thin. You can, however, use cleaner to prep them for ABS cement.

 

[Waynebonnelljr@gmail]

Joining PVC is considered call solvent welding.

You are making 2 pieces of PVC 1.

The job of the primer is to soften the PVC so when you apply the "glue" it will cause the 2 pieces to combine on a molecular level so the 2 are now 1.

Years back we used to do whole houses not using any primer, then we started using it, then the purple primer was required. The purple primer was a disaster as it would not allow the joints to set right and they would pull apart minutes later sometimes. Then they went away from that and back to regular primer.

Joints made with out primer could be easily taken apart with a hammer and flat head screw driver

Why is it necessary to use primer when gluing PVC joints? Wouldn't glue alone be enough?

 

[Waynebonnelljr@gmail]

I've read most comments on this topic and Cass is most correct. Glue also could be used alone if you know what your doing but primer is faster. The primer does actually penitrate into the PVC faster. Keeping your joint wet is most important throughout the process. While doing your next joint read the can. A quarter turn is necessary to join these two surfaces together. I believe you can't always achieve a quarter turn but even small twist back and forth while surfaces still primed will suffice. The more you believe in this theory the more you'll practice the correct way. Priming is not coloring the pipe. Can glue do this alone? Yes. But, you have to do it right. Just remember the theory... Melt the pipe with solvent materials twist into place and your golden..

 

[Cfipp]

Here is a very interesting study on the subject:
The Great PVC Primer Debate
https://www.plumbingsupply.com/the-great-pvc-primer-debate.html