Any idea how to get this cured silicone out of the 20mm deep cavity? It is at joint which is making it difficult to remove.
u/album-dumbledore — 1 day ago
r/moldmaking
Cheapest way to make a mold
I have worked with silicone and resin a bunch. I used to have large tubs of smooth on and it worked great but it's pricy.
I have a missing oh shit handle in my car. It's an import and I have not found a replacement handle. I have the handle on the other side and could make a mold of it but don't want to spend much to do it. It would be a one time use mold, likely. I tried caulk but over more than a week it never fully cured.
What is the cheapest way to make a simple but somewhat detailed mold for making a resin copy of something?
u/Big-Cream9352 — 1 day ago
▲ 1 r/moldmaking
Silicone vs alginate
Hello, I'm wanting to get into vulva and breast casting. Could somebody kindly tell me if silicone or alginate would be more appropriate for this? Pros and cons of either? Thanks a lot ☺️
u/Bubbly_Name_7009 — 3 hours ago
Why 90% of injection molding problems don’t start at the machine
In production, when molded parts start showing flash, inconsistent dimensions, or unstable ejection, the first reaction is often to adjust machine parameters.
But in many cases, the real cause starts much earlier.
Recently we reviewed a mold where repeated flashing appeared around a side-core area. Processing parameters had already been adjusted several times, but the issue kept coming back.
After checking the mold, the main causes were surprisingly simple:
insufficient fit accuracy between moving components
wear developing faster than expected under production cycles
small tolerance accumulation between several mold components
None of these looked serious individually, but together they created instability during mass production.
A small component deviation can easily become a recurring production problem.
In our projects, we usually pay more attention to component fit, wear resistance, and long-term repeatability before the mold enters production. In many cases, that reduces adjustment time later and helps avoid repeated troubleshooting on the machine.
I’m curious how other teams approach this.
When you see recurring flash or unstable molding results, do you usually start from machine settings first, or from mold component inspection?
u/Flora-Wu — 3 days ago
▲ 3 r/moldmaking
I have been trying for the past two months to get a good mold of a balloon, here are all the things I tried:
- Two part silicone balloon made with smooth on 20 and 40, with a plaster and burlap mother mold
- One part alginate mold with a plaster cast, so I can more easily make a two part silicone mold (this didn’t work because whatever I filled the balloon with wasn’t more dense than the alginate)
- Two part plaster mold (I mean, you can tell why this wouldn’t work lmao).
Please, I’ve got intermediate mold making experience, but this has been one of the hardest molds I’ve ever made and I can only find one video on the internet about it and he does the first process and I just figure there’s a simpler way. Maybe there isn’t because of how a balloon deforms; its density and etc…
please someone give me some suggestions, I’ll try anything.
u/FelixEditz — 6 days ago
I'm looking to make a couple concrete sculptures of this figure here (shown here as an example, wanted to test small scale direct printing of molds), but looking to scale it up to roughly 40cm high.
To make the full sized model I'll be casting off I'm intending to either carve it out of polystyrene with a hot wire cutter, or failing that print the whole thing. I won't be making lots of them, probably just a couple, so I'm not sure if it's worth going the full route of latex mold and fibreglass mother mold due to cost etc.
Are there any other ways a couple of concrete casts of that scale could be done cheaply? Would making a two-part mold from plaster of Paris work and be effective? Any tips appreciated!
u/FirstyPaints — 13 days ago
▲ 87 r/moldmaking
This was for the 1:4 scale creature puppet I designed for Color Out of Space, I wanted the skin to be run in one piece (except for a couple of extra legs) so we did the whole thing as a matrix which transitioned to just grp for the heads of the creature. It had a grp core for the body and 3d printed cores in the heads which were connected to the body-for via floating spectra spines. Build recipe and final cast included at the end of the gallery. Parting lines determined by myself and master-mouldmaker Giulia Scati (who did most of the actual work here from walking to glassing). I ran the matrix, the body core and the final rubber, head mech’s designed and printed by the wonderful Tom Tuohey. Body sculpt by McGregor Allen, heads sculpted by me, legs sculpted by Dan Gomer (I think). Many excellent other crew helped out along the way.
u/13fingerfx — 12 days ago
▲ 2 r/moldmaking
FDM print to Silicone mold
I am currently experimenting with silicone moulds, and I am thinking on creating my own. The challenge I want to address is the best way to get rid of layer lines. I have 2 option:
1: Print the mold, cast the object with gypsum(or other material). Sand the gypsum until I am happy with it, create the mold from the gypsum object.
The reason for this option is that I consider easier sanding gypsum than PLA.
2: Print the object, make it smooth, and create the silicone mold from it.
Option 2 have less steps, however I am worry that sanding and filling the PLA would take longer than expected. Since once I got the silicone mold I will not need this piece anymore. Is ther a dirty and quick way to smooth PLA?
Any suggestion would be appreciated
u/meronder — 5 days ago
How would you make a mold for this piece?
Explain like im 5 yo please, maybe 4 piece mold?
u/JlcTg — 5 days ago
I started writing a reply to a post by u/cc-2389 but it got real long and I though if I was going to spend this long essentially reducing a 20 hour class I used to teach down to the most salient points, I might as well make it its own post, in case it might be useful to others.
Despite the abridging, it will get quite dense by the end so please do ask if you have any questions, as it can be a lot to take in.
(I will dictate a lot of this for speed and so I can do this while I’m sculpting, so please excuse any errant capitalisation. I’ll do my best to scan it for typos before posting.)
Silicone rubber - overview
Silicone Rubber can be broken down into two main types (there are others, though… that’s foreshadowing): addition cure and condensation cure rubbers.
Condensation cure (a.k.a. tin cure) silicone, is cheaper, easier to use and, unfortunately, not suitable for prosthetics. It also shrinks a bit as it cures (due to the condensation of its name).
Addition cure (a.k.a. platinum cure) silicone, is more expensive (it uses platinum as a catalyst instead of tin, after all) and much easier to contaminate, but it’s almost universally at least cosmetic grade (some are food grade, some are medical grade) and it has almost 0% shrinkage.
Notes on contamination:
Platinum‑cure silicones use a platinum catalyst but their very specific reaction can easily inhibited by many contaminants such as sulphur or materials containing amines (watch out for modelling clay that contains sulphur, many do), latex, tin‑cure silicones (ironically), some resins (many urethanes), and some paints, also cigarette smoke and aloe vera! When these contaminants are present on a surface (or worse) mixed in, they deactivate the platinum at that interface, so the silicone exposed either never cures at all or forms a thin, sticky inhibition layer instead of a clean surface. Ultimately, a little contaminate can ruin a whole pour, though more commonly it will give you a final piece with a sticky, unpaintable surface that loses fine detail and will not bond properly to skin or encapsulate.
Shore hardness:
Shore hardness is a measure of how soft or hard something is. There are several different scales but for FX purposes you will likely only encounter three of them:
Shore 00, Shore A and Shore D.
You can see a visual representation of these scales here.:
Many Silicones will have a number in their name, usually this number relates to the shore hardness.
While a moulding silicone will likely have a shore A hardness of around 20 to 25 (sometimes as high as 40 or 45), when we are making prosthetics we want far softer rubber, to accurately replicate the movement of human biological tissue.
The first (and, in the opinion of many, including myself, the best) silicone rubber formulated specifically for this purpose is Plat Gel 10 from Polytek. As you would expect from the name, this has a shore hardness of 10 on the A scale, but this is still much harder than human fat tissue. To use it for prosthetics it is chemically softened, which requires a chemical additive which was devised in partnership with special effects artist Gordon Smith, whose name is still used for this additive.
Deadener (full name “Smiths Prosthetic Deadener”) is added to a mix of Plat Gel 10 (often referred to simply as PlatGel, even though there are now different types) to drastically reduce the shore hardness. Note, it also reduces the viscosity (useful for pouring or injecting into moulds) and slows the cure time (sometimes unhelpful as it opens it up to environmental inhibition).
When added to PlatGel 10, Deadener lowers the cured Shore hardness. With increasing deadener loses “snap” and rebounds more slowly, which is why it resembles fat tissue. It also develops a more dampened, viscoelastic response, so it moves and wrinkles more like real skin and subcutaneous tissue. Mechanistically, the additive interferes with and dilutes the effective crosslink density of the platinum‑cured network while still allowing the silicone to cure.
When a prosthetic artist talks about a % of deadener, they are referring to the mix of chemicals used to achieve the desired softness. The % is comparative, representative of the value compared to the total weight of the plat-gel 10 being used, not as a part of the combined weight.
Most prosthetics made of PlatGel 10 are run at around 150-200% deadener. Normally one will know the desired weight of the final piece and the desired % (softness). So the challenge is working out what those requisite weights are.
The values can be calculated with this equation:
Where
W = total mix weight (A + B + D).
p = desired deadener percent relative to (A + B), written as a number (for example, 200 for “200% mix”).
A = PlatGel10 part A weight.
B = PlatGel10 part B weight.
D = PlatGel10 part A weight.
And where A = B (it always does).
Assuming you know the value of W (usually estimated based on the weight of clay used when producing a mould and adjusted for subsequent runs) then we solve this equation for D.
D = (W/(p+100))*p
Similarly you you can solve for A or B with this equation.
A or B = (W/(p+100))*50
Below I will break down an example 175% mix, for a 250g batch.
W=250g P=175
D = (W/(p+100))*p ∴ D = (250/(175+100))*175 ∴ D = (250/275)175 ∴ D = 0.9091175 ∴ D = 159g (rounded off)
Similarly, you can solve for A or B with
A = (W/(p+100))*50 ∴ A = (250/(175+100))*50 ∴ A = (250/275)50 ∴ A = 0.909150 ∴ A = 45g (rounded off)
We can check the results by adding our answers together. Remember A=B
We want the results of close to 250g (forgiving rounding errors)
So, if A=45g and B=45g and D=159g
A+B+D= 249g
That’ll do, Pig. That’ll do.
I know this will almost certainly feel horribly overwhelming, almost none of us got into FX because we love maths, but this is pretty easy when you get the hang of it. I also wrote a web app a while back that I’ll try and dig out a link form which does the work for you, but it’s worth being able to do it yourself (with a calculator, you’re not a mathalete. Or maybe you are. I don’t know your story.)
Good luck and please, do ask questions.
Afterword:
Some other stuff to remember: Silicone deadened to beyond 100% will start to be super sticky even when cured (this is different to inhibition) and will require “encapsulation” to be functional. This can be done with cap plastic (if there’s enough interest I’ll do another post on that) or via a layer of un-deadened silicone (straight a+b) stippled into the mould.
Silicone is a pain to paint and can really only be painted with more silicone. While you can use single part silicones (acetoxy silicones, a third kind!) the solvents requires to break them down into a paint or pretty unpleasant. The best option is a product from smooth on called Psycho paint and they sell a solvent for it called NOVOCS, which is so named because it contains no volatile organic compounds (VOCs). This means it is not giving off any toxic fumes, although you will still need to wear a respirator if you are air brushing, obviously. It is also worth noting that NOVOCS is just hexamethyldisiloxane under a brand name, and you might be able to find it for cheaper from a chemical supplier than by buying the smooth on bottle. In the UK it is available under the name Di-Clean.
For the same reasons that it is hard to paint, silicone can be hard to stick to things. You can either embed fabric into the silicone when you are running it and then stitch it to things (be wary of any fabric with latex based elasticity) or you can adhere it with low modulus, acetoxy Silicones. Options for these will vary depending on where you are in the world, but in England we either use a Dow Corning product called Dowsil or another called Silpaint (I forget the manufacturer). Some stink of vinegar as they use the evaporation of acetic acid to cure, but some, like A07 from Wacker, use toluene which is toxic as fuck, so be careful.
Lastly, other Silicones it is worth knowing the name of, there are two other types of PlatGel: 00 and 25.
PG00 has a base shore of 30 on the 00 scale (about equivalent to pg10 deadend to about 100%) and is great for prop limbs, et cetera. They have also released PlatGel 0030 and 0020 but I’ve not had cause to use them because of the variability of the other options.
PG25 is a very low viscosity rubber with a shore of 25A that has its own deadener called LV (for low viscosity) and which has an entirely different effect ratio. Also, you can’t encapsulate a softened appliance or piece in deadened PG25 because the shore of the unsoftened rubber is too high and it will split when the soft rubber beneath flexes.
When Polytek released PG25 they also included a hardener additive that raises the shore as high as A40.
That’s all I have for you for now but if anything is unclear or if there are any other aspects of prosthetic or general fx work you’d like me to cover in similar detail, feel free to ask.
u/13fingerfx — 12 days ago
▲ 2 r/moldmaking
Help making a mold of this custom lego hairpiece?
I sculpted this custom lego hairpiece and i want to make copies of it with resin
after asking around from people who have done things similar, the 2 products I was recommended were
Silicone: Mold Star 15 slow
Resin: Smooth Cast 65D
A few tries in and im realizing the shape makes it extremely difficult for the resin to fill in all the spikes
Is a vacuum chamber non negotiable for something like this?
u/_i-hate-redditors_ — 3 days ago
▲ 1 r/moldmaking
To make a two part mold, you have to embed part of the piece in clay right? Like melt down some monster clay and set half your piece in it, then pour the silicone, etc. But what if you're making a mold from a piece made with monster clay? How do you embed monster clay in monster clay? Do you just coat it in something? I'm so sorry for my possibly very dumb question. I've only made one part molds and I've never used Monster clay, but I have some and I'd like to use it
u/Grocklette — 9 days ago
I got my old melt’n mold factory from my mom but it’s missing all of the molds & attachments. Is there anyway to use this without the standard molds? I had the idea of using tinfoil but I’m wondering if anyone here has any ideas.
u/Liverspots598 — 11 days ago
Hi all. Thanks for any help.
I’m looking to fabricate a “high roof” for a van.
Basically same shape as a small boat. Should I do ABS or fiberglass with aluminum frame? I’d love any other ideas. Upside down boat is tempting, but I’d rather learn how to fabricate such a thing.
u/Simple_Pin_8781 — 6 days ago
▲ 1 r/moldmaking
Hi,
I have a plaster mold and I want to replicate it on my CAO software (Fusion 360).
I need the interior shape of this mold (the curve and other things).
Do you know some tool, tips, or math formula ?
I thought to put some soft material inside it, demold and trace the outline, then scan it and send the image in CAO, but I don't know what type of metariel to use to not damage the plaster mold, and stay firm when demolding.
Do you have any clue ?
u/FloLaco — 12 days ago
Hello, I am trying to get into different materiales to combine with others. One of the material I'm most interested in is a resin material, I actually have difficulty knowing which type of resin these studios use, it might be epoxy or polyesther, or something else maybe.
Besides that, I would love to hear some recommendations on any books and how to use this material. How to combine colors, what materials are needed, etc. Full info on this, I would really appreciate it.
I have seen jewelry, lamps, furniture made out of this and I'm 100% sure it is a resin because some studios share their process. I have one book in mind about color combinations and how to achieve certain colors which is "A Dictionary of Colour Combinations" — Sanzo Wada but idk if there are any better ones than this
Thank you so much
u/JlcTg — 9 days ago
▲ 0 r/moldmaking
Hey all,
I'm very new to mold making. I've been trying to make a 2 part mold of a, for lack of better terms, bowl using 3D printed PLA as the mold itself (shown in first 4 images) with platinum cured silicone casted into the mold. The PLA has been coated in a thin layer of XTC-3D to avoid microbubbles escaping from the voids in the 3D print. The mold is split down the middle making two quarter spheres and when combined make a half sphere ~18 cm in diameter. In addition to screwing the mold together at many points along the seam, I also created a gasket (seen in red in image) to hold the two parts together and create what I thought was an airtight seal between the two. The gasket was also covered in a light coat of vacuum grease. I also line the outside of the seam with hot glue. However, when placing the mold inside the vacuum chamber I still get some air bubbles at a few points along the seam which make their way into my silicone part.
I've tried making just a normal bowl mold in the past, but it was damn near impossible to remove the silicone part from the mold without partially destroying the mold and part, especially when I use a 3D printed bowl inset to create an actual bowl with a thin (~1cm) shell. The finished silicone part I want is shown in the last 3 images. This part was made with a single part mold and it was damaged in the process of removal...hence why I made this 2 part mold so it could be easily removed.
Notes:
- Link to .STEP file of the mold is included if anyone is interested in looking at it
- I have to use platinum cured silicone for the part.
- There will be multiple layers to the silicone part and I need control over the thickness of each layer, which is why I'm using a 3D printed mold.
Anyone have any recommendations on how to improve the overall design to create a seal that can work under vacuum or design considerations to avoid creating a seam down the middle?
TLDR:
I'm trying to make a 2 part mold made of PLA and casted with silicone that when placed in a vacuum chamber does not experience bubbling due to an improper sealing where the two mold pieces connect. What's the best way to do this or design considerations to improve design?
Link to .step file:
https://drive.google.com/file/d/1RXJazqe4nX_puGaPApj6s_Sz1V8o7ZPh/view?usp=sharing
u/The_White_Dynamite — 13 days ago