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Discussion Starter #1
Been trying to do 2 part molding and it always seems to be missing parts. Each time I remold the same casting its a different part. I would like to mold without adding filler to correct it. Any advice what I am doing wrong.


Thanks in advance
 

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Wish I could help ya, but since I changed locations and the air quality is much different and not as controllable as my old place, I'm getting alot of pits, and the resin is comming out soft at times...
It sounds to me, you may have a humidity problem too... I have put a dehumidifier in and am having much, much better results with my first run... I don't have to do anymore filling and the pieces release much better too...
Hope that gives ya a tip... Good luck !!!
 

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Discussion Starter #3
Wish I could help ya, but since I changed locations and the air quality is much different and not as controllable as my old place, I'm getting alot of pits, and the resin is comming out soft at times...
It sounds to me, you may have a humidity problem too... I have put a dehumidifier in and am having much, much better results with my first run... I don't have to do anymore filling and the pieces release much better too...
Hope that gives ya a tip... Good luck !!!
That could be it, it seems the resin is not filling all points of the mold.
This stuff is time cunsuming and expensive, especially when you have to correct it with filler then sand..
 

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is your mold perfect? or does that have the holes as well?your best bet i think would be get some resin thinner, thin a tiny bit out then brush on a layer over the mold and let it set up some and pour the non thinned resin into the mold..or can jut brush the resin on and pour it in...brushing will make sure you got a good coat on all surfaces as air bubbles can get trapped under the resin.
 

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Discussion Starter #5
is your mold perfect? or does that have the holes as well?your best bet i think would be get some resin thinner, thin a tiny bit out then brush on a layer over the mold and let it set up some and pour the non thinned resin into the mold..or can jut brush the resin on and pour it in...brushing will make sure you got a good coat on all surfaces as air bubbles can get trapped under the resin.
The mold is perfect, just the resin not traveling to all points. It might have to do with the way it has to stand when drying. If I lay it down to dry the resin will leak out. Brushing some in sounds like the best bet.
The next mold I will extend the points to air pockets and cut off.

Thank you.
 

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try to brush it on,that would be the best method its what fiberglassers do when they do small molds and they dont use a spray gun for gelcoat, if you just pour it in, it creates air pockets due to gelcoats thickness...so as i suggested, paint it on, let it tack up then pour it in. then it should not leak out either...might want to post a picture of your mold as well...but like you said if the resin is not traveling to all points it needs to have some brushed on. hope it works out for you
 

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Resin issues

I can sincerely say that having resin issues over the past 10 years is why I have decided to make most of my customs parts, by hand forging out of silver soldier. They are not easier to make, there is no duplication and every piece is a prototype. It is resin issues are so frustrating and very messy. All of the advice I have read from Stangfreak and opie_7afe are all good advice. Like Steve (Stangfreak) I live in a high humidity area and that is a resin complication. Trying to keep your resin fresh is a key component in quality pours. Always shake you product about 30 minutes before pouring. Always keep your lid on your products, (Especially the hardener) and use Liquid Nitrogen to cap off your bottle of hardener after every use.
There is a place out of San Diego that has it for about $10.00 a can. This is where I buy my resin. Remember Like the silicon, this stuff has a shelf life, and If you are not going to use it right away then buy smaller quantities. Chances are you will be trowing some away eventually. I'm glad Steve got the dehumidifier, him and I had just had this conversation recently.
As far as getting the resin down to the deep cracks and crevices and getting a complete casting, Using the brush works excellent, as long as you have plenty of brushes to use. Poking with tooth picks or semi sharp objects and releasing the air bubbles helps too. Working with a slower resin helps too. What we are supposed to be doing is use a vacuum chamber that sucks the air bubbles out.That's expensive and creates its own issues. What really worked well with me when I was making a master to be molded. I would put thin vent tube attached to areas that I would think would be a problem getting resin too. People are a prime example. the arms are long and narrow and it is easy for air bumbles to get trapped inside and when you go to de-mold the character, there would be half of a arm missing. The answer was, on your original to be molded attach a small vent tube that would allow the resin to travel past the end of the arm and pushing the air bubbles out the tube. This works well, it just needs some forethought on your behalf before you pour your silicon mold. I hope I helped. I can almost write a whole book on this subject. (I think I almost did here, At least a chapter. Hope all goes well for ya
 

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i wonder if you could make a quick vac chamber from a shopvac and a clear box strapped down to a board with some gasket where the box will sit. just enough vaccum to remove the airbubbles and flow the resin into the voids and such...just a random thought!
 

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i wonder if you could make a quick vac chamber from a shopvac and a clear box strapped down to a board with some gasket where the box will sit. just enough vaccum to remove the airbubbles and flow the resin into the voids and such...just a random thought!
I have thought about it but I am not sure if the shop vac would produce enough to do the job. It would be great to be able to use it for the silicon mold makng also
 
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