How on earth do I do this?


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Wends151
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Hi everyone!

Slowly driving myself mad so after some advice if you don't mind?

Attached is an image of a thick block memorial paperweight I'm trying to make. No matter what I do, I can't seem to get it to an acceptable level of finish (this is one of MANY I have tried). The attached is where I was trying to be clever (subjective word I know!) and 'glue' the butterfly and acetate in place with a few drips of resin (to stop them moving from position), then unfortunately I let it fully cure (it should have just gelled but I forgot about it) before topping up to just under the brim and putting in a pressure pot to fully cure. I left it in the mould then topped it up with a thin final layer of resin, spritzing and torching away micro bubbles before covering and letting fully cure. Yeah, not a great result?!

Apart from trapped air behind the butterfly, you can see where the original resin has been used and/or inadvertently dripped?! Also, despite it only being a thin layer over a largeish surface area and being torched and spritzed with isopropyl alcohol, there are still gazillions of tiny bubbles?! In short, it is so amateurish it is not funny!

I'm using an epoxy Total Cast casting resin but am wondering if I should be looking at a different resin and/or technique completely? Any advice would be greatly appreciated.x
Chris Rogers
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Not sure if its a good idea and have no direct experience with doing it to epoxy - but you might look into pressure casting to minimize the bubbles.  I know it works for clear urethane and other casting resins and makes incredible bubble-free parts.  You could probably do it in a painting pressure-pot.  60-80psi (4-5bar) works great in some situations I have seen but not sure what would help with epoxy... 

Also, maybe degassing the resin? 

Good luck!




Wends151
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Chris Rogers - 2/4/2020 2:55:10 AM
Not sure if its a good idea and have no direct experience with doing it to epoxy - but you might look into pressure casting to minimize the bubbles.  I know it works for clear urethane and other casting resins and makes incredible bubble-free parts.  You could probably do it in a painting pressure-pot.  60-80psi (4-5bar) works great in some situations I have seen but not sure what would help with epoxy... 

Also, maybe degassing the resin? 

Good luck!

Thanks Chris but this is the result after it's been in the pot? Because you get the meniscus dip I've topped up that last couple of mm to the brim and I'm getting air bubbles from that. And this is despite warming the resin on a seed mat, measuring and stirring slowly, torching and spritzing the surface and then covering it?! 

Warren (Staff)
Warren (Staff)
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Not knowing the resin system you are using, it is hard to tell if the resin is at fault or just a change in method needed to get best results.

Certainly with our GlassCast range of resins, the sooner to the start of the B-stage of the cure, the less likely you will see a join line between pours (B stage is firm but tacky). Degassing can always help as long as you have a suitable pot life to do it.  With organic material you may need to seal it first as the resin can soak in releasing bubbles or have some reaction. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
Wends151
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Warren (Staff) - 2/4/2020 5:08:51 PM
Not knowing the resin system you are using, it is hard to tell if the resin is at fault or just a change in method needed to get best results.

Certainly with our GlassCast range of resins, the sooner to the start of the B-stage of the cure, the less likely you will see a join line between pours (B stage is firm but tacky). Degassing can always help as long as you have a suitable pot life to do it.  With organic material you may need to seal it first as the resin can soak in releasing bubbles or have some reaction. 

Thanks so much for your reply Warren. I'm using an epoxy TotalCast. Once it's in the pressure pot, do I not need to leave it in there until it cures?

I am looking to get a vacuum chamber as I make my own moulds too. When you say a suitable pot life, how long would that be? My epoxy system starts gelling at around the 60 minute mark so would I still be able to de-gas it?

Wends151
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Wends151 - 2/4/2020 7:36:46 PM
Warren (Staff) - 2/4/2020 5:08:51 PM
Not knowing the resin system you are using, it is hard to tell if the resin is at fault or just a change in method needed to get best results.

Certainly with our GlassCast range of resins, the sooner to the start of the B-stage of the cure, the less likely you will see a join line between pours (B stage is firm but tacky). Degassing can always help as long as you have a suitable pot life to do it.  With organic material you may need to seal it first as the resin can soak in releasing bubbles or have some reaction. 

Thanks so much for your reply Warren. I'm using an epoxy TotalCast. Once it's in the pressure pot, do I not need to leave it in there until it cures?

I am looking to get a vacuum chamber as I make my own moulds too. When you say a suitable pot life, how long would that be? My epoxy system starts gelling at around the 60 minute mark so would I still be able to de-gas it?

Also, another question I wanted to ask was, is it possible to de-gas the resin separately? i.e. put the resin and the hardener in separate pots and de-gas them then mix together and do a final shorter combined de-gas?

Warren (Staff)
Warren (Staff)
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Depends on the resin system - the manufacturers data should give you the proper pot life etc.

You can degas the parts of the resin separately but you will add air to the mix when mixing so it would not be that beneficial.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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