I needed to make a repair on some PVC pipe. When I opened my can of cement, I discovered that is was thicker than when new. I purchased the cement around a year ago and kept the lid firmly closed. The can is about 2/3 full. I could still easily spread the cement around the pipe. At what point is the cement no longer viable? Can it be made viable by thinning it with PVC primer? Yes, I should go purchase a new can of cement.

  • Have you considered simply testing the glue on a couple pieces of scrap pvc? Aug 6, 2014 at 13:22
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    What is the pipe's purpose? Water drain, pressurized source, other?
    – James
    Aug 6, 2014 at 15:46
  • Good question James, in a non-pressure application it might not be that big of a deal. Aug 6, 2014 at 21:31
  • Sometimes it's non pressure, sometimes it pressure. Assume pressure.
    – Les
    Aug 7, 2014 at 17:35
  • This begs the question, in a non pressure application does one even need the cement? The list of ingredients indicates the primer alone may create enough adhesion, in fact plain acetone might.
    – Sae
    Apr 20, 2019 at 14:22

7 Answers 7


I use MEK (methyl ethyl ketone) available at most hardware stores. It has always worked for me and I've never had a fitting failure yet. I have had fittings fail from using thickened glue. Granted it's not the best thing to do, and I always buy a new can as soon as possible. But I do know where you're coming from when you need to do something to be able to finish a job, and can't run to a store at 3 am, or when you are 30 or more miles from any supplies.

Being that is the main ingredient in most welding adhesives or glues. Look at any MSDS Sheet and you will see the solvent used in it. For example: http://www.speedlinepvc.com/user/pdfs/5152-pdfs-5-file.pdf

I know I'm satisfied with my results. And storing that can upside-down always helps. I've even spread a bit of the glue around the top of the can to dry into a seal if I know I'm not going to use it for a really long time.

  • Why would storing it upside down help?
    – Steven
    Jan 2, 2015 at 15:18
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    Maybe storing it that way would keep the can sealed from air intrusion? Clarification from @Grapenuts would be best.
    – Doresoom
    Jan 6, 2015 at 15:12

Primer contains the same ingredients as Cement, except Cement also has PVC resin in it, so theoretically you should be able to add primer to cement to thin it.

Oatey Purple Primer contains Acetone, Cyclohexanone, Tetrahydrofuran, and Methyl ethyl ketone.

Oatey Regular Clear PVC Cement contains Tetrahydrofuran, Acetone, PVC Resin, Cyclohexanone, and Methyl ethyl ketone.


PVC cement works, in major part, by creating a chemical weld between the two pieces. If it has thickened, that means there's less solvent, which means it probably won't dissolve/weld into the two pieces as well. It may "work", but the joint is likely to be weaker than it would be with a fresh can. Whether it's good enough is hard to predict, and depends in part on what you're using it for.


A little thicker or gummy? If it is gummy at all do not use it for a pressurized application. I have tried it in a pinch because I did not want to make the time killing run to the hardware store and the joint blew out two days later, it literally came unglued. You would have thought that it would blow out at initial introduction of pressure, right? No, it waited; with evil intent, until I was not home and flooded the yard and garage.

I applied it as directed, clean fittings and pipe plus primer.

  • 1
    This doesn't really answer my question. Is thinning a viable option? As you mentioned, the time killing run to the hardware store is what prompts me to ask the question. By "thicker or gummy", do you mean in degree of thickness or is gummy a different sort of property?
    – Les
    Aug 7, 2014 at 17:34
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    I know, "gummy" is a bit subjective. If it spreads onto the pipe without pulling itself off or clinging to the applicator it might be OK. If you stir it and it clings, it is getting gummy. Hard to explain but I guess time and experience tells me when the consistency warrants throwing it away. Thinning will not work. +1 for the good clarification question. Aug 7, 2014 at 20:03

You sure can, friend. All you have to do is keep mixing until you get it to the consistency you want. Just know that whenever you break it down, it's not going to hold as well as an un-thinned cement.


Have you tried acetone? The PVC cement I use lists acetone as one of the solvent contained therein.



I'm out in the Styx and have used the ol lady's fingernail polish remover to thin the PVC glue. Never had a problem . It has acetone in it and works fine.

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