Not sure which forum this belonged in, but being body I figured this would be an appropriate spot.

I have some silver POR-15 left over from when I gave the bottom of my drivers door a POR bath to stop the rust before it ate the door any worse and while it was still in a repairable state. It came in the starter kit with the 3 small cans, the cleaner and the surface prep. The third can I opened up and used a small amount of then put the lid back on tight with some wax paper as a seal between the lid and the can. This was about 2 years ago...

What I'm wanting to do is use this leftover amount to coat the welds on my subframe connectors which currently have surface rust due to the spraypaint flaking off then once the POR-15 dries cover that with some undercoating. I have exactly the right amount of POR-15 left to do all the welds. However, here is my dilemma:

I know that he company that makes POR-15 specifically states that after a can of POR-15 is opened, it only has a limited shelf life before it has to be thrown away. I think it was something like a few months. Can't remember but I know it wasn't long. My question is, why? When I shake the can, the contents are clearly still in a liquid state inside and have not hardened into a big block of POR-15. I'd like to save myself the money of ordering more of the stuff if I can. What happens if I use it?

 

Usually, the way I gauge quality of POR 15..
If I can get the lid off of the can, it's still good.

 

haha same here man. ive had my por 15 for about a year and a half. i started putting mine in a ball jar cause itl stay good forever.

 

if it's fluid it's OK. It dries from moisture in air so if the can was kept closed it should be good for a long time. I always poke a hole in the lid and seal it w a screw dabbed in the por residue around the hole from pouring it out. it'll stay good for a very long time, especially if you keep it in the fridge