Bluefish Molding Question?

[Ken's Fish Taxidermy]

Well I posted this also in the Molding section and thought I should post it here too. Sorry If I am not supposed to post twice. I have 25" to 30" in bluefish I am going to be molding. Will the Smooth-On PMC-744  48oz. kit be enough to mold both sides of the fish? I am going to be using high fiber and a pexi-glass box to pour the mold. Like that video with the bluegill. Can't remember where I saw it though. What I was planning on doing is Gluing the pexiglass sections together with caulk or something so when the mold sets up I can remove it. Fill the bottom of the box with high-fiber and lay the fish in it. Set the fins and make sure everything is in line. Set the keys and spray on the PVA mold release. Once the rubber set up do the same on the other clean side second half, remove mold keys, PVA, then pour the second half. I think I haven't forgotten anything and I if I did please let me know. This will be my first try at molding a fish so any help would be appreciated.

Thanks
          Ken

[CrabCrazy]

don't know about the smooth on, but if the fish is frozen, you will have to inject caulk or something under the skin , as this type fish tend to have a lot of depressions, if they are not fresh

[Doug Bridges]

Ken, I think there are better materials to use than urethane rubber. PMC 744 is a good product, but I think you would be better served to go for a silicone product. As for the size of fish and the amount of material that you need. Length x width x height (in inches) will get you the volume of your mold that you are building. Then multiply by
Total cubic inches x 0.00432900433 = US gallons of material.  If you use that measurement x .8, then you will have a good estimate of the material that you need. If you measure for 1 half then times 2. 48oz will be no where near enough material if you are pouring a block mold. Now if you are doing a skin mold and then making a support shell, you may get 1 side done with that amount.

I think you would be better served to make a skin mold (thin walled mold) of silicone and then make a support shell out of Plastipaste or fiber glass or thickened urethane plastic for your application. For the silicone, you can use Moldstar 16. That has a pot life of seven minutes and a demold of 30 mins. It'a  a platinum, so you need to keep all sulfur containing material away. That includes well water with sulfur in it, sculpting clay with sulfur, etc.  Back that up with a hard shell, turn the fish and repeat.

[Ken's Fish Taxidermy]

Ok thanks for the heads up. I was already anticipating that I would need to do something like that. So just inject the caulk in the area where its indented and it should fill up back to its normal form? Doug how many pulls would you get out of the mold the way you suggested? Thanks.

[CrabCrazy]

just fill it back to its original shape....don't over do it

[Doug Bridges]

Depends on how you build the mold and how you treat the mold. Platinum is a durable material. I won't put numbers on it, but you can expect many pulls from a well built mold.

Question to you. How many pulls do you want to get from the mold. I think that is the first place to start when you start a new mold making project.

[Ken's Fish Taxidermy]

Just a few probably. Its my brothers fish he caught and thought it would be a good fish to try doing this. So I am going to do the same thing with the box and high-fiber. Lay the fish in it and position everything, add mold keys, spray mold release. Would PVA work with the Moldstar 16? Then after the mold release is applied dry it and then put a medium coat of Moldstar 16 silicone on. This layer should catch all the details. Then after that is cured make the support shell with the PlastiPaste. How much would I need of this stuff. I wouldn't think that much because it is a skin mold. Then after the PlasticPaste sets up I could do the same to the other side. By the way I am looking at Smooth-On's website. Trying to go as less expensive as possible. Would bondo work? 

Thanks for all the help.
Ken

[Doug Bridges]

No need for PVA with silicone.
No need for a mold release on the silicone either to do a fish.
One thing you need to know about moldstar. It's a thin viscosity material. It will run. So, you will need to tend to the material as it is setting. Maybe the best thing is to pour a thin coat over the fish, let that set and then pour additional material over top and use a brush to move the rubber as it cures over the fish.
Second thought. You may be better off to go to a tin based rubber, Mold Max 30 perhaps, and do the same process. Since you are only looking for a few pulls, there is no need to spend the big $'s on platinum rubber. Look at the cure times though.

[Ken's Fish Taxidermy]

Ok thanks Doug. I like the sound of that a lot! Should I buy it from there website or is there a cheaper place to get it from? Thanks so much for the info and help! I will post pics of it when I am done with the cast. Could you pm me some prices that would be great. What does tin based mean? Do I just add the catalyst and it starts setting like bondo? I plan on making the mother mold with fiberglass sheet and resin. Thanks for the help.

Ken

[torka]

why not just use bondo and fiberglass resin with a layer of fiberglass for strength, as described by Gary Bruch in breakthrough. not sure if it an option or not as this is new to me also.