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Landry

Anyone make degassed silicone molds???

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I make large 6-11oz (9-12”) muskie soft baits and have been using silicon molds (mold star 30) in mold boxes for 4 years now. 


I am pondering going to aluminum molds but this is a big pricey move for me as I need at least 6 molds made. My reason to move to aluminum is that with my silicone molds I need to pour three junk plastic baits through each mold in order to get the baits to come out smooth without tiny dimples on the surface. The dimples go away after that so that had me thinking they were not air bubbles in silicon causing the problem but instead some type of gas or cooling issue (mini denting). 


Before I jump into aluminum, I was pondering buying a pressure chamber and pump to degas the silicone and get rid of one possible variable. In the meantime I am currently pouring a new mold with mold Max 60 (60 shore) in thin layers to hopefully eliminate micro bubbles as a test run  - perhaps the harder silicone will help too????


Was wondering if anyone here has seen degassing or moving to a harder silicone get rid of this micro dimple issue?
 

Thanks so much guys. 
 

 

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Sounds like you mite just need to warm the mold before pouring ?

 If so, not sure the proper way to warm silicone molds. 

 Maybe pour it with a color you can cut up and reuse.

Maybe a Hair dryer.

 I do know after they get heated up they hold the heat and maybe to much heat .

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4 hours ago, Bass-Boys said:

Sounds like you mite just need to warm the mold before pouring ?

 If so, not sure the proper way to warm silicone molds. 

 Maybe pour it with a color you can cut up and reuse.

Maybe a Hair dryer.

 I do know after they get heated up they hold the heat and maybe to much heat .

Yes - heating in oven does not work as well as with junk plastisol pours to warm them

my question is - will a firmer and degassed silicone enable me to pour clean molds right away or in less time???

my guess is that I will have to buy a degassing setup and test it myself. Lol. 

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Interesting.  I degass some of my molds so that I don't get that problem when I use expanding foams in them, but never considered that any tiny dimple that would go away would be caused by that.  I wonder if it because of micro temperature differences due to air pockets close to the surface.  :unsure:

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Most of my lure making invoices silicone molds and I never degas the silicone without issue but there are 2 things that can cause dimples 

1) your mold is only as good as your master. I clear coat my masters and this makes things super smooth. My hard baits comes out with a slick finish even

2) when making your mold pour a thin layer covering your master and stop. Wait a minute or two before pouring the rest. This will give time for small bubbles to come to the surface and pop. Blowing on it or a blow dryer helps. This will create a smooth skin around your master before pouring the rest of your mold. This is extremely important when using mold release because it reacts to the silicone creating more bubbles 

from what you are describing I am betting you used mold release an poured the silicone all at once. This creates a cavity full of dimples. Been there done that lol

My molds have smooth pour cavities but if you cut up an old mold the middle is full I’ve bubbles 

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On 3/18/2021 at 4:05 PM, Hillbilly voodoo said:

Most of my lure making invoices silicone molds and I never degas the silicone without issue but there are 2 things that can cause dimples 

1) your mold is only as good as your master. I clear coat my masters and this makes things super smooth. My hard baits comes out with a slick finish even

2) when making your mold pour a thin layer covering your master and stop. Wait a minute or two before pouring the rest. This will give time for small bubbles to come to the surface and pop. Blowing on it or a blow dryer helps. This will create a smooth skin around your master before pouring the rest of your mold. This is extremely important when using mold release because it reacts to the silicone creating more bubbles 

from what you are describing I am betting you used mold release an poured the silicone all at once. This creates a cavity full of dimples. Been there done that lol

My molds have smooth pour cavities but if you cut up an old mold the middle is full I’ve bubbles 

I did all of those tricks and my masters are glossy and smooth. One of two things was happening to make the dimples:

1. Micro bubbles in the silicon even though I laid a thin coat first

2. The soft silicon was off gassing possibly?

the high temp mold Max 60 May be what fixed the problem OR it may have been that I laid down multiple thin layers so had no bubbles anywhere near the bait surface. 
 

nevertheless, I bought a degassing setup and am now making high temp firm silicon molds the right way. Molds that can handle 6-12oz of hot plastisol without giving me those dang dents right away. No more pouring recycled junk plastic through my molds for an hour before I get the quality I want. 

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17 minutes ago, Landry said:

I did all of those tricks and my masters are glossy and smooth. One of two things was happening to make the dimples:

1. Micro bubbles in the silicon even though I laid a thin coat first

2. The soft silicon was off gassing possibly?

the high temp mold Max 60 May be what fixed the problem OR it may have been that I laid down multiple thin layers so had no bubbles anywhere near the bait surface. 
 

nevertheless, I bought a degassing setup and am now making high temp firm silicon molds the right way. Molds that can handle 6-12oz of hot plastisol without giving me those dang dents right away. No more pouring recycled junk plastic through my molds for an hour before I get the quality I want. 

I am not sure what is going wrong I use mold Max 30 following the steps I mentioned and it works.for me

I am pouring pike lures so more mid sized not as large and maybe that is the difference 

My experience is mostly using it for hard baits and only a handful of soft bait molds so my luck might change in the future 

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13 hours ago, Hillbilly voodoo said:

I am not sure what is going wrong I use mold Max 30 following the steps I mentioned and it works.for me

I am pouring pike lures so more mid sized not as large and maybe that is the difference 

My experience is mostly using it for hard baits and only a handful of soft bait molds so my luck might change in the future 

I think it is the 340° heat that causes it. When I pour hard resin in to make a clone of my master carving it comes out smooth. 
pretty sure I have the solution now with degassed high temp silicon 

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2 hours ago, Landry said:

I think it is the 340° heat that causes it. When I pour hard resin in to make a clone of my master carving it comes out smooth. 
pretty sure I have the solution now with degassed high temp silicon 

I am using it for soft plastic too but poured around 325 for temp. Still green with soft plastics so this is only a small number of pours 

either way go with what works for you is always the best option. Post your results on degassing as it might be helpful for others 

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I watched a youtube about making dice molds and the guy was having the same sort of issues especially since he was pressure potting the resin as it cured. IIRC degassing the silicon helped lots but curing the mold in the pressure pot was the answer i'll see if I can dig that video up. 

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I also have the same issues as Landry with Specialtyresin silicon molds specifically!! I have to pour remelts through them as using an oven or microwave to pre heat them is not enough. Doesn’t seem to be as pronounced with other silicon like polytek or alumilite. Molds/masters are clean! Once it breaks in for the day, the baits come out smooth as clean glass, but it’s a grumble to get to it. My guess here is there is some sort of chemical/gas release taking place despite de gassing, unless it’s de gassed a second time right before it goes in. Whatever chemical trace or film is left behind, inhibits the release of the gas. Not really 100 on this because it’s my experience and I don’t have the science to explain it. 
It’s a real drag and I just can’t produce efficiently when this happens. So I like the shore 60 idea which I’m going to try before switching out all of my molds

This might be a case of getting what you pay for. A gallon of specialty is way less than a gallon of say polytek. 
 

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On 4/10/2021 at 12:27 PM, RedRum said:

I also have the same issues as Landry with Specialtyresin silicon molds specifically!! I have to pour remelts through them as using an oven or microwave to pre heat them is not enough. Doesn’t seem to be as pronounced with other silicon like polytek or alumilite. Molds/masters are clean! Once it breaks in for the day, the baits come out smooth as clean glass, but it’s a grumble to get to it. My guess here is there is some sort of chemical/gas release taking place despite de gassing, unless it’s de gassed a second time right before it goes in. Whatever chemical trace or film is left behind, inhibits the release of the gas. Not really 100 on this because it’s my experience and I don’t have the science to explain it. 
It’s a real drag and I just can’t produce efficiently when this happens. So I like the shore 60 idea which I’m going to try before switching out all of my molds

This might be a case of getting what you pay for. A gallon of specialty is way less than a gallon of say polytek. 
 

Well my results are now definitive. 
High temp mold Max 60 properly degassed gives me clean pours immediately- it may work with 30 shore too but I have not tried it yet. 
I have made two new molds are both are incredible. 

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I had same results with 60. 40 on the other hand still dents and bubbles.
although, if I remelt, de gas and then pour in the softer (pre heated molds) they come out great the first time, then all the pours after are really nice

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