The great PVC primer debate

I make lots of kayak-related things using PVC pipe. When I glue PVC pipe together, I never use primer, and always figured I was giving up some strength, but also figured that as a practical matter, it was probably not enough to matter.

I came across this article today, which provides a ton of experiments that show just the opposite, that is, the joint is actually stronger without primer. Now I'm glad that I never wasted money on primer.

Anyways, just thought I'd pass along the info...

https://www.plumbingsupply.com/the-great-pvc-primer-debate.html

Timing is everything, thanks for the article. My exterior water system developed a leak where the former owner used a black iron fitting at the joint between the supply (copper) and the rest of the system PVC. That fitting and the PVC are like permanently bonded to each other, any more force on it would probably break the PVC where I wouldn't want it to break. If I cut it off I'm going to end up with about 5/8' usable PVC pipe stub. Because of it's placement between foundation and sidewalk and sprinkler manifold,,,,, I have one shot at a repair without doing a whole lot of digging. Of note I have never used primer in ~50 yrs of doing PVC piping and have never had a leak. This time however because of the work involoved if the first repair doesn't work I was going to consider it.  Also of note in the results was the performance of the All Purpose cement.

I was a landscape contractor for about 30 years. We used to use primer, but I think the blue glue, and especially the “Red Hot Blue Glue” or similar wet/ dry glue doesn’t need it. Maybe the older slow -setting gray glue needed it.

Timely post, as I've re-done a good bit of my back yard irrigation in the last couple weeks.  Mostly 1/2" drip line stuff, but a couple sprinklers and risers, valves, and a new timer.  Lots of holes.... I'm thankful for the recent and frequent rains to keep the ground easy to work with.  On the plus side - almost done! Plants are in the ground, everything has water, and all the different ground cover materials are in the correct places.  Just gotta build a pergola, but we might wait a little bit for that.

On that, I used the purple primer and clear glue - they came as a set and the glue said to use the primer.

I was a landscape contractor for about 30 years. We used to use primer, but I think the blue glue, and especially the “Red Hot Blue Glue” or similar wet/ dry glue doesn’t need it. Maybe the older slow -setting gray glue needed it.

Hey Joe, I'm an actively working landscape contractor! 

One of our specialties is irrigation. I was told something by a manufacturer rep for Spears (the company that makes all the PVC fittings) that made me a primer believer.

Primer does two things. 1) cleans the pipe 2) softens the pipe. When you add glue and twist the fitting a little, the glue, primer, and pipe all gell together into what Spears refers to as a "Solvent Weld" because it is literally fusing the two pipes together. (Conversely, this is why you shouldn't use too much or get messy with the primer)

Christy found out their exceptionally aggressive red hot blue glue had properties similar to primer and held up great with no primer in lab tests. Labs are devoid of dirt, grease, imperfect prep, inexperienced helpers, water, sunbleached pipes, and inconvenient installation locations. Therefore I choose primer every time as cheap insurance. It takes longer but I sleep a little easier that way.
 

Careful with declaring 1 internet source as state of the art...
I'm not going to join the ensuing conversation.

Hey Joe, I'm an actively working landscape contractor! 

I'm a Landscape Architect these days. No more worries about equipment and crews.
If we have any projects in Sonoma county, do you bid on full projects?
Our website: www.huettldesign.com

Yes - most of our revenue comes from projects and one-time service & repair projects like the busted irrigation I was alluding to. We do a little maintenance (but it's mostly for our old build clients to keep them from looking old.)

We're always ready to help more good designers implement.

Our website is www.callwingle.com. Happy to jump on a call or a zoom or send references from another designer.

And finally - I wasn't trying to throw shade -  yall's PVC kayak projects are likely good-to-go with the right glue and no primer. As long as you didn't build them in the rain... or in a muddy pit.. or with 50 year old crusty pipes in an awkward spot under a sidewalk where you couldn't quite get a nice cut and de-burr job on it... 

Careful with declaring 1 internet source as state of the art...
I'm not going to join the ensuing conversation.

Always good advice, but if you look at the info provided at the link that I posted, he did a large number of experiments, and the results clearly show that the pipe/joints are stronger without primer. Of course, there could still be reasons to use primer in some cases (for example, perhaps it improves leak resistance), but for kayak-related things, I only care about strength, and I'd say that this is overwhelming evidence that no primer is the way to go for me...