I am mostly a militaria collector, but recently acquired a few replica pistols I would like to make casts of to use in displays and such in my collection. Essentially, I want these to be good replicas that can be used in holsters and hands of WWII mannequins, however I also want them to be tough enough that they can be used as training replicas at work, and take a hit or two being knocked down. Understanding that resin is fragile by nature, I'm keeping my expectations in check.
For the silicone mold, I have read that Alumilite HS II is a pretty good product, easy to use, minimal bubbles, and captures detail very well.
As for resin, I have read good things about the durability of both 300 and 45D, but it seems that 45D handles impact better and is often preferred for weapon replicas. Any feedback on this? Currently leaning towards the 45D.
Finally, I would need to dye the resin black. I'll admit I haven't really gotten into this part yet, so I have to dig around, but off the cuff, does anyone have a good/preferred type of coloring they use in these situations they recommend?
Yes the HS-2 would be good to use, you could also use the HS-3 as both of those will work pretty much the same and it's just a little difference in the "stiffness" between them and how much you'll be using them. If they're going to be full sized replicas, I'd suggest the HS-2 would be better as it's stiffer and would hold the weight of one better.
Okay I'm not sure where the 300 and 45D are from but for what you want, I'd recommend the Alumilite Performance 80D which is more of a "plastic" type resin which would handle the training impacts better. Also Alumilite has special dyes that can be used to color their resins. From the videos, it takes only a few drops to completely color the resin.
Thank you for the response. How are the details of the 80D?
I have been thinking of making a double mold, obviously only one piece could be cast at a time, but figure it would save space and reduce silicone loss of making to molds. Essentially side by side, with the pour and vent holes near the grips like shown in the image below. Is there any issues with molding a piece like this (inability to firmly clamp it, etc), or would a double mold be feasible?
Yes a two piece mold like that should be a good thing. For a two piece mold, that's going to be a mold that needs to be a little stiff to hold the shape well when pouring while still getting all the detailing picked up so the High Strength 2 (or even the HS 1) would give better support than the HS 3
For the clamping,I'd place the mold between two pieces of wood (can be as thin or as thick as you want) to give the mold halves good solid support all the way up and down each side. You'll need to "burp" the mold while you pour so that all the air bubble can escape so having it sandwiched between two pieces of wood is helpful in keeping it aligned and in shape.
For the vents, I'd leave off the ones on the left side of the picture as if you use the right side as the pour hole you will have the resin coming out the other end.
Now there is another way you could do a two piece mold without any vents and that's by pouring each side as a 1 piece mold and then "gluing" the two halves together after demolding. It will give each side more of an area for bubbles to escape and you'll be pouring each half separate instead of in one shot but it might work better. For a "hard" resin like RC-3 you could just superglue the halves and go from there but for anything "flexible" you would have to use a small amount of the resin as the glue to make them bond together. Or you could do what I do when I make rubber stamps with the Flex 50 - I pour it into the mold, wait until the 4 minute open time is up and keep watching until it's hard enough to demold (it should pull away from the sides but still is sticky) then before the 2-4 demold time is up I demold and stick it to a piece of wood. As long as it hasn't hit full cure, it will bond nicely to anything you stick to it - got one that I actually tried to get off the wood and it refuses to let go no matter how hard I pull on it.
Now as for doing the two halves of the mold, you can use clay to fill up the first half or use it to hold the piece in place while you pour that half but personally I like to use ReMelt instead of clay as it just seems to clean up easier to me. But be sure to have a release agent (Petroleum Jelly works great) between the two halves or you'll have to cut the mold halves to remove the piece after pouring the mold.
Thank you for the information, but the mold I am proposing is not a two-part mold with halves for a single item, but a single mold with two separate models. The two vet/pour holes are because they would be two different one piece casts, so only one would be made at a time, since the spouts would be in different areas. It seems that your info above would largely apply to this concept, too, however
Ah that explains the vent holes on both ends - where you have the vents would work just fine in that case. If you do a one piece mold with a seam line, you'll still need to clamp it or your casting might end up shaped oddly. One piece molds don't need as much support but with the size you want it's always a good idea to be sure it is supported well. And be sure to do the "burping" part or you might get voids in spots you have to later fix.
A two-part mold with halves is mostly for ease of removing the casting. For yours, you'll have to be sure to cut the mold around the trigger area or you won't be able to remove the casting. Anything that has a hole that the mold material can go through needs to have a spot where it is cut or your casting won't come out - I know how much trouble holes are to cut when they go from one side to the other so I just save myself a little trouble by doing halves for anything that has holes as I can make the cut area without cutting the casting out later.
You can do a one piece mold but you'll need to put some kind of "line" in the trigger area so that the mold material doesn't flow all the way through. A thin piece of clay (if you shape it and bake it that would hold its shape better) or even a piece of paper (well secured) will work fine. Silicone won't stick to anything other than silicone so you can use just about anything as a barrier to prevent the mold material from going all the way through the hole area.
I think I will go with halves but still keep it as two separate pistols in it, so will only cast one at a time. I don't necessarily need to make these two at a 1:1 ratio, I don't want to have to always make one when I make the other