resin cures before mold full

[Eddie]

Hi I have just made my mold and tried the first pour, My mold is 5 litres of rtb rubber in 2 parts with a half pint (300ml) cavity and an undergate/bottom filling mold with a pour spout with long runner to the bottom to allow it to fill with no air.

Trouble is the resin is cureing when the mold gets to about half full... Does this mean my mold channels need opeing up more or should I invest in a slower cureing resin.

Sorry for the numpty beginner questions but I am one of those..

Cheers Eddie

[Pinselknecht]

Hey Eddie,

what kind of resin do you use? Type? Curing time? Pot live time?

PK

[Eddie]

Hi there this is what I am using .

Cheers Eddie

http://www.dwrplastics.com/product-info ... in-1kg-Kit

[mangozac]

Obviously wider channels will allow the resin to flow faster, but you might also need to search for a resin with a longer pot life...

[Eddie]

Thanks, Sadly the shape dictates a fill hole that is about 1.5mm diameter. I have however been treating this mold as a prototype and intent to make another and have learned much on the way.
That said its molding flawlesly so far. Just a shame I only have half of my item..

Would lower viscosity resin help.

Cheers Eddie

[Fleafa]

The viscosity is already pretty damn low on that resin! Slower cure is your best bet.
Some photos and diagrams would help us give more advice.

[mangozac]

1.5mm is a tiny fill hole. You really need to consider maybe a second fill hole as well. Fleafa is right in that a photo would be very helpful

[Eddie]

Hi thanks yes I will take some photos soon, However I have already embarked on making the second mold and feel I have learned enough to make a better second mold.

But before I do. What size channel should resin flow faster into, I am thinking about 4 to 6mm width should help,

But each question leads to another so,
1. is plasicine ok to make channels.
2. what size
3. how best to make a bottom fill mold do I need to think about back pressure of air as the cavity fills to a certain amount would the air remaining int he reducing cavity push back on the resin as it exits out the gas outlet causeing the resin to slow in filling, as I notice it seems to take longer to pour in as more goes in..

4. How do I get smooth sharp edges with plasticine . Any tips.

Cheers Rob

[mangozac]

You can make channels out of whatever the hell you want! If I want resin to flow fast I usually go for something around 6-8mm diameter.

I've not done bottom fill so I can't really comment on it. I don't think it's that complex.

Sharp edges with the clay requires the use of a sculpting tool and water. Dip the tool into water and then do the smoothing - you'll notice it works far better than a dry tool. Saliva works even better. I've heard that water based "personal lubricants" are the best thing to use, but am yet to try it myself