Thread: Mould release for PVC pipe

Originally Posted by Tiny James

so I've just had a look at some video's on casting round blanks and they look to be using different PVC pipe to you.

You are using pipe for waste water if you look at there mould they are using pipe intended to supply water under pressure so I would think the inside walls of that pipe is designed to have a very smooth walls so partials in the water will not stick where the waste pip is finished to a lower spec.

I would change your pip first to 16/22 mm supply pipe used in pluming I think it's called flow right it is available at b&q

look at his pipe

James

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Thank you! I think you might be right, I’ve been looking at the pipe and it is quite rough inside so I think I’m fighting a losing battle.. I tried 4 different releases yesterday - Vaseline, a specialist spray silicone, another non silicone release spray and a cheap graphite oil spray i picked up from Lidl for something else a while back. The only one which released was the graphite oil one, but it was still a struggle and I’m not sure if it was a one off.


I bought the pipe I have from B and Q.....I bought both types of pipe they had in stock; this and a barrier pipe. The barrier pipe looked promising...the pipe was smooth on the inside, but my first trial of resin stuck to it like glue

the pipe I would try is speedfit 22mm here is the link JG Speedfit 22BPEX-78028 Push-Fit PE-X Pipe 22mm x | PEX Pipe | Screwfix.com and John Guest Speedfit Plastic Pipe - 22mm x 2m | Wickes.co.uk it's even available at amazon and ebay screwfix is open on Sunday's so is wickes let me know how it goes

James

Originally Posted by Tiny James

the pipe I would try is speedfit 22mm here is the link JG Speedfit 22BPEX-78028 Push-Fit PE-X Pipe 22mm x | PEX Pipe | Screwfix.com and John Guest Speedfit Plastic Pipe - 22mm x 2m | Wickes.co.uk it's even available at amazon and ebay screwfix is open on Sunday's so is wickes let me know how it goes

James

Thanks very much, they seem very similar to the barrier pipe I got from B and Q, so maybe I’ll have another go with that tomorrow, repeating the experiments with the different mould releases, and see if it’s any better. Hopefully one or more of them will do the trick!

Thanks very much for your help!

Following with intrest this is on my get round to it list

Just to report back- I tried the barrier pipe I had, with all of the different releases, and none of them will release. So I think my only option is to cut the pipe lengthways and then secure it before pouring the resin in. Hopefully that will allow it to release.

Hi M, have you tried honey wax
Buy Honey wax for glassfibre, GRP mould surfaces - East Coast Fibreglass Supplies

Originally Posted by fingwe

Just to report back- I tried the barrier pipe I had, with all of the different releases, and none of them will release. So I think my only option is to cut the pipe lengthways and then secure it before pouring the resin in. Hopefully that will allow it to release.

Sounds like a good idea.

Polyester casts in PVC can work in part because PR shrinks a little while curing. Epoxy and Alumilite don't shrink so are that much harder to get out. I think you should either go to the clear tube casting where the tube is left on the blank when done and you turn it off when you want to make a pen. Or you make your own moulds from silicone that can be flexed off the cast blank. Tin cure silicone (pink) works well with PR and Alumilite and platinum curing silicone (blue) is needed for epoxy and Alumilite. You basically make a plug that will be the finished blank and anchor it in a mould, plastic container, box etc. Wax it or spray with mould release and then add your silicone rubber. Degassing under vacuum is recommended and if you will be pressure casting then pressure the silicone unless you use a stiffer one. The higher the number the stiffer and harder the cured silicone. When cured pull off the silicone and you can then put in some mould release and cast your blank. When a blank cures you can flex the silicone to get it off. Make a good mould and take care to always put mould release in it and you can get 50 to hundreds of casts from it. I've used a PTFE dry spray lubricant as a mould release (made for the job) the few times I cast epoxy because I don't like silicone lubricants in my woodworking shop. It contaminates everything and causes fisheye problems with finishes.

Pete

Have you seen our vertical casting moulds Melanie? These are what we cast all our round blanks in using Alumilite.
Quality Casting Moulds for Pen Turners, including our own unique Less-Resin Mould.

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