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Making Two-Part Plastic Molds?

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Any easy DIY ways to make a 2 part mold for soft plastics? I've thought about it, but I'm having trouble figuring out ways to keep the two halves from fusing during the mold making process.

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I guess it depends on what your mold it made of...

 

pour a mold that covers the blank half way up .

 

cover the protuding blank with a mold release and also the surface of the mold

 

then when you pour the second half it should be able to separate when cured.

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I have used bondo to make a two part mold for lead. Mixed the first batch to do the first half of the mold, then sprayed WD40 on the bondo after it was set for a release agent. Fill up the rest of the way, then separate the mold when dry to remove the model and cut a fill spout. May be something like this will work for plastics too? I'm wanting to try it when I get some time so if it works, let us know.

 

Jigman

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View PostI have used bondo to make a two part mold for lead. Mixed the first batch to do the first half of the mold, then sprayed WD40 on the bondo after it was set for a release agent. Fill up the rest of the way, then separate the mold when dry to remove the model and cut a fill spout. May be something like this will work for plastics too? I'm wanting to try it when I get some time so if it works, let us know.

 

Jigman

 

 

Sounds good. I'll give it a shot next weekend, pending time and materials.

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I made one out of RTV and did as above by filling half then after curing, spraying with mold release and pouring the top part. When you make the bottom half Put some marbles half exposed near the cornors. Then before pouring the second half remove the marbles or whatever you used to leave the holes they came out of. The second pour will fill the holes and create registration marks to align the two parts when pouring. Ues release agent liberally.

 

Also consider whether or not your mold will need vents to let out air in distant or curved corners otherwise you will have bubbles and missing parts on the final poured product. Google Larry Dahlberg and watch his online videos.

 

Also if you can get away with a flat top lure, silicone caulking mixed with water makes a great inexpensive mold. Search this site on silicon molds.

 

Good luck and show us the results.

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I've successfully made two piece, soft plastic molds from POP, sealing them with a 50/50 mix of water/Elmers Glue All.

RTV will work very well but is expensive while POP is next to free.

Here's what they look like.

6". 1.5 oz. deep bellied Swim Bait.

DSCF0001-51.jpg

 

DSCF0002-40.jpg

 

DSCF0003-33.jpg

 

DSCF0004-23.jpg

 

DSCF0005-14.jpg

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