# Casting Resin=Vacuum ?



## Nowski (Dec 19, 2015)

Is there a casting resin that works well with vacuum? I have some knife blocks that have some small voids that need to be filled but are too big for epoxy.


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## manbuckwal (Dec 23, 2015)

Nowski said:


> Is there a casting resin that works well with vacuum? I have some knife blocks that have some small voids that need to be filled but are too big for epoxy.



I think pressure is the recommended route for casting, in part because the pressure also po_ps bubbles that might_ form

Reactions: Like 1


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## JR Custom Calls (Dec 23, 2015)

I've heard people say you can cast using an older table saw that vibrates real bad, but seems everyone prefers pressure


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## gman2431 (Dec 24, 2015)

JR Custom Calls said:


> I've heard people say you can cast using an older table saw that vibrates real bad, but seems everyone prefers pressure



When we used to mix 2 part stuff we would use an old palm sander that just vibrates and get the bubbles out. It was also said to help mix it. An old timer showed me that a long time ago.

Reactions: Useful 1


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## chanser123 (Jan 15, 2016)

Most cast with pressure pots.


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## CWS (Jan 15, 2016)

You can also you ultra sonic cleaners to vibrate bubbles out

Reactions: Informative 1


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## Schroedc (Jan 15, 2016)

I've just started getting into casting using clear resin and don't have a pressure pot yet. Using PR and the vibration of my router table has worked pretty well to make the bubbles float up. I'm getting ready to start using Silmar 41 resin (I was using a comparable resin but it isn't water clear which is why the switch) I can keep you posted on results.


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## kweinert (Jan 15, 2016)

I use a modified HF paint pressure pot. Here's an Instructable that describes it: http://www.instructables.com/id/Bubble-Free-Resin-Casts-with-Modified-Paint-Tank/

There's a lot of interesting discussion in the comments as well.

Reactions: Informative 2


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## Final Strut (Jan 15, 2016)

PR will work for filling voids in wood only to an extend. The biggest problem with PR and voids is the shrink rate of the resin. Fiberglass grade resin that has an amber color to it has more solids in it and doesn't shrink as much as Silmar 41 but it is difficult to color. There are several things that you can do to try to control the amount of shrink but it takes a lot of trial and error even after being coached by guys that seem to have it all figured out. 

Alumilite works hands down the best for filling voids and casting waste wood but requires pressure without question.To get any resin deep into cracks and the like you need to cast under pressure. Contrary to populate belief pressure does not pop the air bubbles it simply compresses them to a microscopic size. I have had PR blanks that I have pulled out of the tank to soon bubble on me because once it hits the atmospheric pressure the air bubble will re-inflate so to speak.

Pourable epoxy will work for filling small voids and doesn't necessarily need pressure even though it helps but it doesn't finish up as nice as PR or Alumilite. The biggest thing to be careful with when using epoxy is to make sure the voids you are filling aren't to big because it will overheat as it cures and you will have a far less than desirable blank when it is all said and done.

If you are doing solid acrylic blanks or tube in type casting PR works great and you do not need pressure and as others have said vibration helps a lot. While I have not tried it, I have heard of guys trying to use vacuum to cast and it has created a lot of mess and I have been told that you will only try it once. 

I hope all of my rambling helps somehow

Reactions: Thank You! 1 | Informative 1 | Useful 1


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## Tj King (Jan 16, 2016)

Schroedc said:


> I've just started getting into casting using clear resin and don't have a pressure pot yet. Using PR and the vibration of my router table has worked pretty well to make the bubbles float up. I'm getting ready to start using Silmar 41 resin (I was using a comparable resin but it isn't water clear which is why the switch) I can keep you posted on results.



I would be interested to see this!


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## Brain M (Jun 18, 2016)

I watched a guy on YouTube cast alumilite exclusively with vaccum. He was using a converted air compressor that he turned into a large vacuum pump. He says it's how he cast all his blanks and they looked very nice. I would love to start casting but needing to buy more tools right now is just out of the question. I just purchased a new vacuum chamber set up so I might just try it with some resin from hobby lobby.


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## jasonb (Jun 19, 2016)

I cast alumilite with a converted HF pressure pot too. Picked a used one up for $40, so wasn't to expensive. Below is a good ref between vacuum and pressure casting.

Reactions: Informative 1


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## Brain M (Jun 19, 2016)

This guy uses a vacuum and gets great results? Is this a different type of resin?


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## jasonb (Jun 19, 2016)

Same alumilite resin, would've like to see him cast a clear blank.

Reactions: Like 1


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## Brain M (Jun 19, 2016)

Might just have to try. Worst thing that happens is I need to save up for a pressure pot....

Reactions: Like 1


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## rocky1 (Jun 19, 2016)

Final Strut said:


> While I have not tried it, I have heard of guys trying to use vacuum to cast and it has created a lot of mess and I have been told that you will only try it once.
> 
> I hope all of my rambling helps somehow



Actually it does help, as that would make a lot of sense. Given set time of most acrylic resins, if you're pulling vacuum on it, you are probably still going to be pulling bubbles, as the resin sets. I suppose it would be possible if the blank was stabilized and all voids were filled, and all you were pulling was bubbles out of the resin itself, but otherwise I can definitely see that making a mess of your casting on a clear pour. Dyed it probably wouldn't be as obvious, and one could of course fill any voids with CA as you turned.


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## rocky1 (Jun 19, 2016)

kweinert said:


> I use a modified HF paint pressure pot. Here's an Instructable that describes it: http://www.instructables.com/id/Bubble-Free-Resin-Casts-with-Modified-Paint-Tank/
> 
> There's a lot of interesting discussion in the comments as well.


 

Thank you Ken!! Have everything sitting in the shop to pour the silicone molds, simply haven't done it yet. Did not realize they should be degassed during curing to prevent warts all over your casts and mold damage in future pours. Makes sense after reading though! Saved me 1 course in the school of hard knocks!

Oh yes... likewise looking at the HF pressure pot to pour castings. Simple, easy, inexpensive.


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