Thread: How to not get bubbles when injecting

Do you have bubbles in the cup before you shoot? Not all molds are equal some will trap air if not properly vented.


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No bubbles in the cup before.

Are you getting bubbles or is the mold not filling properly?

Try letting plastic rest for a minute or so after heating. Look for trapped bubbles stir real slow.
I pour directly from the cup into injector put cap on then push until I get the air out.

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I don't know what type of plastic that you are using. also if you are staring too much you are going to get a lot of bubbles in whatever you do when you're stirring do not use wood use a metal steering rod also like it said above if your mold for not properly made so the air can escape when you are shooting you are going to have problems make sure that all the error can escape properly again do not over mix your plastic. I won't get into the issue on plastics but some of the different plastics have more bubbles than others when you are mixing them. in which mold are you having problems with.

Thanks Guys,

I am using a mold from Jacobs Baits and the plastic I am using now is from MF. I have started not stirring as much and at the moment I am just using a 14mm wrench because I don't have a metal rod. Maybe the shape of the wrench is causing it? Also, how would I know if the mold isn't properly made? If I pour it when it is too hot would that cause bubbles in the mold? I don't see visible bubbles in my plastic when i put it in the injector and the bubbles in the baits are big enough that I would see them in the Pyrex cup.

Originally Posted by JKR06

Thanks Guys,

I am using a mold from Jacobs Baits and the plastic I am using now is from MF. I have started not stirring as much and at the moment I am just using a 14mm wrench because I don't have a metal rod. Maybe the shape of the wrench is causing it? Also, how would I know if the mold isn't properly made? If I pour it when it is too hot would that cause bubbles in the mold? I don't see visible bubbles in my plastic when i put it in the injector and the bubbles in the baits are big enough that I would see them in the Pyrex cup.

I sent you a PM .

after you draw your plastic, are you turning the injector upside down at a 45 degree angle(ish), and slowly pushing the plunger until a solid stream of plastic comes out, to purge the air from the injector tube?

Originally Posted by H2oHammer

after you draw your plastic, are you turning the injector upside down at a 45 degree angle(ish), and slowly pushing the plunger until a solid stream of plastic comes out, to purge the air from the injector tube?

you were exactly right I guess I forgot to mention that but I usually shoot some plastic out of the injector before I put it to the mold that was one of my biggest mistakes when I was starting out.