Why is resin casting more prone to bubbles than other materials?

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Why is resin casting more prone to bubbles than other materials?

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Because it’s thick/sets fairly quickly so when stirring vigorously you are adding in oxygen bubbles.

When I work with resin I tap tap tap tap to encourage the bubbles up to the surface, obviously can be difficult depending on the shape you are working with, but that’s the trick I was taught in school !

Most casting is either done with resin or molten metal; and it happens that resins are “thicker” and have a harder time letting bubbles of gas filter up during solidification. Liquid metal has a “consistency” more similar to water than something like honey, which is what you see with resin. Metal castings also have to deal with dissolved gases, which is a big part of why cast objects have a reputation of being weaker than forged or machined metal objects – there are potentially gas bubbles in a cast object which can make it weaker. Casting is a process which is inherently poorly controlled, so issues like bubbles are something you need to spend a bunch of effort trying to combat.

Yet another way to get the bubbles out is to use a vacuum chamber. They can be made or bought for around $100. You can put your mixed resin in the chamber before pouring and/or after it’s in the mold.

Fun fact, other things like cast metal can have bubbles in them, you just can’t usually see them from the outside because they are not clear like resin.