How many cast are expected?

Questions about Making Your Own Lures

How many cast are expected?

Postby lucky stick » Tue Feb 07, 2012 8:48 pm

How many baits can I expect to get out of a mold made from High Strength 2? Is there preventative cares for getting more baits out of my silicone? Is cold weather bad on the molds? ( right now mine are sitting outside in the garage where it is about 38 degrees)

How many molds could one expect using the mold putty?

I will be pouring mostly white super plastic
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Re: How many cast are expected?

Postby Mike - Alumilite » Tue Feb 07, 2012 11:58 pm

This really depends on the negative drafts and design of the lure but typically in a 2 piece mold those items are minimal so I would expect a yield in the realm of 40-50 parts to come out of your mold. Things to help and avoid:
Do not leave your parts sit in your mold overnight after pouring. Try to demold within 30 minutes.
Use Alumilite's UMR release. This is a paintable mold release when not used excessively. Mold release puts a barrier inbetween the mold and the resin.
Preheat your rubber molds prior to pouring. Warm to remove the cold feel from the rubber which will allow the resin to cure more consistantly and quicker.
Condition the mold every 15 pours with silicone oil. Silicone oil is put on a clean cotton cloth and occasionally wiped into your molds to recondition them. Typically allow the silicone oil time to absorb into the rubber without pouring more parts ... 2-3 days minimum.
Dow Corning use to recommend a bake out process to recondition silicone molds of 2 hours at 400 F to cure unreacted polymers that might be on the surface as well as draw oils within the mold back to the surface of the part to replenish the softer feel on the surface.
Another tip is to paint your mold with your base color of paint. Allow the paint to fully cure and then cast Alumilite White. The White will chemically bond to the paint and you will demold a primed or base coated lure. The paint or base coat will act as a release by not allowing the resin to touch the or try to adhere to the silicone rubber mold which eventually begins depleting the oil and lubricity from the mold surface which starts to feel dry and will eventually crack or chunk out.

Try any combination of these to maximize your mold life. Cold storage will not hurt the rubber. Shelf life on cured silicones is not an issue as long as it is not exposed to chemicals or solvents.

Mike
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Re: How many cast are expected?

Postby lucky stick » Wed Feb 08, 2012 7:02 am

Thanks for the detailed response. I can now tell my buddy it's time to stop wasting his super plastic in his now debunked mold. He would pour his super plastic and when he demolded, his bait was full of air bubbles. He was burping his mold and had a vent in it as well. He couldn't figure out why he was now getting bubbles after he had got about 40 perfect baits.

Thanks,

Mike
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Re: How many cast are expected?

Postby Mike - Alumilite » Wed Feb 08, 2012 9:05 pm

Another possibility for your buddies resin problem is moisture. Moisture in urethanes causes them to foam. If the bubbles are random throughout the part, it could have absorbed moisture and contaminated the resin in which there is not much he can do with it. Typical signs are lots of crusty stuff around the Iso side (B side) which will immediately react with relative humidity and crystalize. In the polyol side the moisture will absorb and you will not know it until you pour a part and the bubbles will form as the resin starts to cure. If there is a lot of moisture in the resin, the material will actually grow/foam.

This typically happens after opening and shutting the bottles many many times and when there is a lot of head space in the containers (most of the resin has been used). Another potential cause is if it is stored in a non temperature/humidity controlled area such as a garage or pole barn.

Just saying this could be a possibility from your description. If it is in the molds, the bubbles would be the exact same on every part.

Mike
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Re: How many cast are expected?

Postby lucky stick » Wed Feb 08, 2012 10:16 pm

So......storing his resin in his sometimes heated garage in Northern MN is a bad idea. I guess I'll learn from his mistake and make my resin a nice spot in the basement.

Early you said that the silicon molds are not negatively impacted by cold. Is it ok to leave the high strength material in the cold before it is mixed?
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Re: How many cast are expected?

Postby Mike - Alumilite » Thu Feb 09, 2012 7:58 pm

Moisture again is the enemy. Storing the chemicals is best if not going through daily swings of outside temps and humidity ... especially northern MN. Shelf in the basement out of the reach of children is a much better choice.

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Re: How many cast are expected?

Postby GMan » Sat Mar 17, 2012 8:31 am

Where can I get the silicone oil and what type do you recommend?
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Re: How many cast are expected?

Postby shenlonco » Sat Mar 17, 2012 9:08 am

GMan wrote:
> Where can I get the silicone oil and what type do you recommend?

Go to a RC hobby shop and purchase a bottel of 100% silicone shock oil get the clear type and you can get the thinist weight i believe is 5wt and 10wt the RC's all use 100% silicone oil mostly in the shocks now adays... I use it and brush on a thin coat inside the mold before i pour the liqid rubber and it makes them come out shiny and you only have to recoat the mold like every 4 pours or so.

and if you want real thin silicone oil get a spray bottle of 100% silicone airsoft spray lube spray some out into a cup and then paint it into the mold... do a search on e-bay you should find it for sure ,,, I use this also and it works great!

Hope this helps.

Shen
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