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nobeerinheaven · 11-29-2012, 08:17 PM

I've searched around and haven't been able to find an answer to the following question: I slightly pierced the side of my mash tun (an 120 quart Coleman) and would like to patch it. Silicone does not work, because it peels off. I was wondering if it would be fine to either (1) melt the plastic slightly with a blow torch until I can push it back together, or (2) melt some other plastic (say, from the lid of an unused food-safe bucket) and patch the hole. It's too small a hole to replace the mash tun, but big enough to bother me.

Would one of those two options work? Does melting the plastic and reforming it sacrifice anything in terms of durability or food-safety?

**LandoLincoln** · 11-29-2012, 08:26 PM

I think the blowtorch idea is just going to make the problem worse, so don't try that.

A heat gun, on the other hand, would give you some better control. Maybe it could work.

steber · 11-29-2012, 08:36 PM

When I used to do autobody repair we did plastic welding. A plastic welder is like a soldering iron but has a tamping foot. In the past I've used a soldering iron to weld with. If you can find a piece of plastic to use as filler and melt it down or should work.. as for being food safe I have no definite answer for you.. I would assume yes, as its the same plastic to begin with. Yet I'm not sure as to what's released chemically when you melt it.

**501irishred** · 11-29-2012, 08:42 PM

How big is the hole? Is it small enough to accept a large diameter SS screw? If so, you could just add silicone or high temp RTV to the threads and screw it in to seal the hole.... Since you wouldn't be able to get to both sides of the plastic, I doubt you'll be able to do much with it if you heat the plastic enough to melt it back together (but I've been wrong before....). Also I'd be worried that the foam insulation would "melt" or contract at a lower temp than the plastic would melt to the point a repair would be possible. They do make glue just for plastic that would work to seal the hole (auto parts store), but I have no idea if it would be food safe especially at 168 deg.

nobeerinheaven · 11-30-2012, 12:33 AM

Thanks for the ideas, all of which are solid. If possible, I'd like the same seamless surface as before (i.e. no screws), so I'm wondering if a heatgun is sufficiently like a blow dryer that I could use my wife's, or if I could get something hot with a blow torch to mimic the effects of a plastic welder. Any thoughts?

Edit: I've also seen people recommend acetone, would something like that work so that the plastic would be more easily molded? The hole is small (the size of a small flathead screwdriver that slipped).

foos-n-brew · 11-30-2012, 03:41 AM

Check out JB Waterweld. It's NFS approved for food contact and will handle temps higher than mash temps. You can find it at Home Depot.

steber · 11-30-2012, 02:18 PM

Quote:

Originally Posted by nobeerinheaven

so I'm wondering if a heatgun is sufficiently like a blow dryer that I could use my wife's, or if I could get something hot with a blow torch to mimic the effects of a plastic welder. Any thoughts?

Edit: I've also seen people recommend acetone, would something like that work so that the plastic would be more easily molded?.

Anything greater than a plastic welder/soldering iron is going to leave you worse off, you want direct/accurate heat. Not a wide area like a blow torch, heat gun or blow dryer is going to give you. Plus you'll want a source of filler. If you're stretching the plastic you're going to make it thin.

I think you should opt for the jb weld suggested. Not to be offensive, but if you have to ask what type of heat to use you're going to most likely make the hole bigger. I don't want to see you completely out of a mash tun.

As for acetone, yes it can make plastic more "fluid" but I'd be worried about some getting stuck in the plastic and leaching out during a mash.