Mould release for PVC pipe

[fingwe]

Hi everyone, I want to start casting my blanks in pvc pipe so they are round, but I’m having terrible trouble getting them out of the pipe. I’m having to cut it off each time. What’s the best mould release to use for alumilite? I’ve tried a couple of silicone sprays but they’ve made no difference. If it makes any difference I cast in a pressure pot at around 50-60psi. And I guess I should also check that I bought the right pipe....white pvc waste pipe from B&Q, it says on it FloPlast 21.5mm white pvc-u O/F pipe....?

Thanks in advance!

 

[21William]

I’ve not tried it with PVC pipe but Macwax is good stuff.

MACWAX Spray Mould Release Agent 400ml - Neills Materials

 

[fingwe]

Thanks....this is what I’ve currently had to go through to get one out, it’s like it’s glued inside....

 

[Paul hd]

I have seen a release agent called Stoner being used on PVC pipe. I just had a look for it but not ready available in the UK.

I think HDPE pipe would be good if you can find that in the correct size.

The blanks look great.

 

[wm460]

Ouch, I would have turned off the PVC tube.

 

[21William]

Yes that blank looks nice. Even with Macwax though I think you may still have a job removing the blank. Silicone moulds are best and easy to make.

Silicone Rubber ideal for moulding materials - Alec Tiranti

 

[fingwe]

Yes that blank looks nice. Even with Macwax though I think you may still have a job removing the blank. Silicone moulds are best and easy to make.

Silicone Rubber ideal for moulding materials - Alec Tiranti

Yes I think you might be right.....there was still silicone residue left on the blanks but it didn’t stop them sticking. I’m wondering if casting them under pressure (or more to the point, the pressure being exerted from the only opening at the top of the pipe) is essentially making them expand in the pipe so they just won’t come out. That said, I did try turning one off and it was like it was glued on.

 

[Penpal]

Silicone for me as well.

Peter.

 

[Tiny James]

Epoxy will not stick to mould release wax and pva (which is blue in colour) check out any fiber glass company for the info you seek

what you do is wax the inside with five coats of wax polish it in-between and after you have the finial wax add a coat of blue pva. as you use the mould release more and more you will find the need for less and less coats of wax until it will only need one or two coats of wax.

if you have around the house dubbing (old fashion boot wax) you could try that and a coat of diluted wood glue but let it dry first

really nice dip pen by the way dreamy colours

James

 

[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

 

[fingwe]

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

d

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

 

[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

 

[fingwe]

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!

 

[Themackay]

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

 

[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.

 

[Bill Mooney]

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

 

[21William]

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.

 

[Curly]

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

 

[Bucks]

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.

 

[fingwe]

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.

View attachment 43341

Thank you, I think they’re the answer....they’re on my wish list for when I get some money!!