Whats the best lid made of?

[kjmc1957]

Hi All

I'm nearly there, got a paint pressure pot, got the compressor and vacuum pump with the fixings, I just need to know what the best plastic type of lid will be, I'm going to do resin infusion and from what I've seen on the interweb it's a good idea if I can see the container under vacuum so that it doesn't over flow the container, that's why I want the lid, so Perspex, Acrylic or something else?

What do the more experienced casters reccommend?

Regards

Kevin

 

[paulm]

Welcome to the forum Kevin. I haven't got a clue about casting, Rowdy is your best bet or maybe one or two of the others. How about showing us some pictures of what you've done so far?

 

[Grump]

Do I get this right?
You want to discard the existing lid that has the pressure gauge, inlet, outlet etc on it and replace it with a home built one so you can see contents under pressure?
If so, dangerous practice I would not recommend you do that.
With the correct stresses and strains figured out perhaps a window in the lid would be possible but I can see no benefit in watching paint dry as it were.

Have you done any of this type of work before?
Are you aware of the expansion rates of the materials you will be using?
Do you know the temperature it will reach while curing / setting.
How do you propose to stop any overflow that may occur?

 

[kjmc1957]

Hi Grump

You need to be able to see the resin in the vessel that is a vessel placed inside the paint pot as a more managable size (lemonade bottle with the top cut off) because when the suction is (introduced? outroduced?) the resin bubbles up in the container, this is controlled by reducing the vacuum level, if you watch any YouTube video on resin impregnation....Turntex/Cactus juice is a good one to search you will see what I mean, unfortunately I'm at work now and YouTube is blocked or I would find a link.

This type of vacuum work is done fairly regularly and seems to be safe, I just wanted to make sure I was using the right material for the lid.

Regards

Kevin

 

[Grump]

I see said the blind man it's all as clear as mud init?
You wanna save your firewood from from the aga.
He has used 3/8 acrylic sheet in what is no more than goldfish bowl, it looks like the vacuum also pulls the lid down to a gasket seal.
Why not do the same?
There is a but here, he has discontinued that model, why I wonder?
From the sound of it he hasn't used much vacuum either, what does your pump produce?

 

[Jimjam66]

As long as the vacuum is not extreme, Kevin, pretty much anything will work. I would suspect you're not looking at much more than 10-15 in/hg at maximum. Given that vacuum would pull any pieces IN (rather than blowing them OUT) I can't see this as a H&S issue. Try a sheet of 1/2" acrylic - should be fine. All said based on my absolutely no experience of vacuum stabilisation, of course ...

 

[kjmc1957]

Hi David

Thanks for the reply. I am interested in what thickness of plastic and as importantly what type of plastic, I understand that some plastics are a bit more robust than others, just wanted to know which was which.

Regards

Kevin

 

[kjmc1957]

Hi All just had a quick peek at e-bay, they seem to be 20mm thick acrylic lids that are supplied, think I'll go for that unless anyone suggests a more appropriate plastic.

Regards

Kevin

 

[Jim]

20MM will be sufficient Kevin, i am sure i have read somewhere that 10mm is the minimum, I will be nipping into my local aquarium shop to ask the guy in there if he will make me a vacuum chamber up this summer...

 

[Penpal]

Hi Grump

You need to be able to see the resin in the vessel that is a vessel placed inside the paint pot as a more managable size (lemonade bottle with the top cut off) because when the suction is (introduced? outroduced?) the resin bubbles up in the container, this is controlled by reducing the vacuum level, if you watch any YouTube video on resin impregnation....Turntex/Cactus juice is a good one to search you will see what I mean, unfortunately I'm at work now and YouTube is blocked or I would find a link.

This type of vacuum work is done fairly regularly and seems to be safe, I just wanted to make sure I was using the right material for the lid.

My sentiments please check on the IAP library articles first.

Kind regards Peter.

Regards

Kevin

Please see above message. Peter.

 

[Lons]

Hi Kevin

I have no knowledge about casting resin but some on sheet plastics as I used to work in the industry.

Polycarbonate would be my choice (without knowing other considerations) as is much stronger than acrylic and is virtually unbreakable in normal conditions. It also has a higher softening point. The downsides are that it is more flexible, (also it's strength) so you would need at least 10 mm thick, more expensive and it scratches and marks more easily as it is softer.

We used to fix a 1000 x 500 x 6mm sheet onto a wood frame and invite people to have a go with a sledgehammer. It would mark like hell but no-one ever managed to break one

Plenty of technical info on the web. Try the main manufacturers Rhom or GE or major distributers like Amari Plastics.

Bob

 

[kjmc1957]

Hi All

Thanks for taking the time to answer this, I'm off too a localish plastic supplies in Cambridge the week after next to pick up an off cut of 20mm.
I'll post it when it's a working kit.

Regards

Kevin