Resin casting newby question...

[tgreco]

can someone let me know if there is a good starter kit or all-in-one kit for molding and casting small pieces pieces in resin

I'll assume it will be a smoosh mold, with a front and back, but the parts are tiny (about .5 inches x .25 inches)

I've never done this before, and I checked out the smooth on site, and while I've done a lot of scratch building, and sculpting, I've never done any molding or casting

and I only need to make 4 so I don't need a ton of resin or silicone

just figure it's the easiest way to tackle this project, so I might as well bite the bullet

 

[MisriahArmory]

Smooth-on is offering 2 trial kits for pourable and brushable molds including silicon, resin and plasti-paste (for the brushable-one).

The pourable one is Mold Max 40 and the brushable is Rebound-25.

2 great silicon products.

 

[tgreco]

Smooth-on is offering 2 trial kits for pourable and brushable molds including silicon, resin and plasti-paste (for the brushable-one).

The pourable one is Mold Max 40 and the brushable is Rebound-25.

2 great silicon products.

is there one that should be the preference for this little job, or would either do?

 

[MisriahArmory]

Depends of the complexity of your sculpture. Also, is it a 3D sculpture like a figurine or something more 2D that can be put flat on a table?

You have to choose between a 1-part mold or a multi-part mold.

 

[tgreco]

Depends of the complexity of your sculpture. Also, is it a 3D sculpture like a figurine or something more 2D that can be put flat on a table?

You have to choose between a 1-part mold or a multi-part mold.

oh, it's simple. no undercuts. it's essentially a light in a square box on a tube
(kind of like a KC light on a truck)
but it would be a 2 part mold as there details on front and back

 

[MisriahArmory]

well if it's small, I would do a 2 part mold using mold max 40 and pour resin in the mold after.

That would be the most cost efficiant way I see.

 

[tgreco]

well if it's small, I would do a 2 part mold using mold max 40 and pour resin in the mold after.

That would be the most cost efficiant way I see.

Thank you!

 

[MisriahArmory]

Follow this tutorial and it will works just like a charm

http://uk.youtube.com/watch?v=LSH19G_6Yeo

Since you'll be using silicon and not urethane, no mold release needed. Silicon don't stick to anything except itself.

 

[BB43MAN]

Try Micromark.com. They sell RTV and various resins that I use for small projects.

Good luck!

 

[tgreco]

Follow this tutorial and it will works just like a charm

http://uk.youtube.com/watch?v=LSH19G_6Yeo

Since you'll be using silicon and not urethane, no mold release needed. Silicon don't stick to anything except itself.

does this mean I should use mold release between the 2 sides of the mold?

pour side 1... let cure... put on mold release... pour side 2
(so side 1 and 2 don't stick together)

the video link was great, thanks again for that and all your help

 

[Reactor drone]

does this mean I should use mold release between the 2 sides of the mold?

pour side 1... let cure... put on mold release... pour side 2
(so side 1 and 2 don't stick together)

Definitely.Silicone won't stick to much but it will stick to itself so a barrier is always needed for a two part mould.Vaseline,wax and PVA glues are commonly used.

 

[MisriahArmory]

Yeah mold release when you are pouring the second half is needed sorry.

but don't forget to use clay for the first half since you need keys.

 

[roadkillonthewe]

Most manufacturers will have trial kits for good prices for first time customers. I have been using Polytek for several years. One thing you must consider when starting is how long you want the mold to last? If you are only going to make one or two castings then you could use less expensive tin based materials that will degrade faster and will not be useable in a couple years or less. I use Platinum based materials and I have molds that are ten years old and I can still use them.
This is half of the first mold I ever built and it worked for ten years before it became so cooked from the heat of curing parts that I had to make another.

The new one has better registration marks to line thing up so I have less flash to remove after the casting cures. Like others have said with silicone molding rubbers you do not need mold release to the original part but if you are making a two part mold you will need it between both sides. I use good old fashioned vasaline

 

[roadkillonthewe]

Also make sure to try a little sample to make sure there is not reaction between the silicone and the item you are pulling the mold from. I have been doing this for many years and recently got screwed on this one.

I put a lot of hours into making a 1960 Thunderbird JR taillight assembly from scratch.

And then I used car model glue and did not allow enough cure time before I started adding the silicone. The silicone reacted with the glue and never cured. I have to redo a lot of my work since it was just a sloppy mess.

Had I let the glue dry for a couple of days I would have been casting parts now and adding vacuum formed lenses to make complete functional taillight assemblies. In the bottom picture you can see the original was damaged during the removal process and will have to be fixed before I can try again

 

[Fulcrum]

Question...
If he does use a silicone rtv mold, Doesnt a mold release help to prolong the life of the mold?

 

[roadkillonthewe]

Question...
If he does use a silicone rtv mold, Doesnt a mold release help to prolong the life of the mold?

I have made a few hundred steering wheels with no mold release. Since they have such a large cross section they generate a lot of heat during the curing process. and eventually it hardened the mold so I made a new one.

The old one would probably still work today but I did not get the part line centered on the wheel so it was geting hard to remove the wheels. I can not speak for the tin products but the platsil 71-20 that I use does not seem to need it. Of course one of the primary reasons you use silicone is for low mold cost over a short production run. If you are looking to make thousands of parts you should go hard tooling. I would have some concern that the mold release would vary the finished part. after all I have one mold that I did not clean a fingerprint off of the master part and now every reproduction part has a fingerprint on it.

 

[Fulcrum]

Thanks

 

[clonesix]

.

 

[tgreco]

I've got the mold made

one side is nice and rubbery and dry

the other side while rubbery has kind of a weird oily feel to it

so I have 3 questions:

did I use too much or too little of the catalyst?

if so will it eventually dry out or does it just need to be cleaned?

is it safe to use it as is?

 

[roadkillonthewe]

What product line did you use?
What side is sticky?
The weeping of silicone and a somewhat oily feeling can be normal as it acts as your release agent. But it should not be that much. can you post pictures to help describe?