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Hello Dakka-ites,

I come, once again, beseeching wisdom from your collective well of knowledge and experience. When you've created a press mould with Instant Mould or an equivalent product, what do use to lubricate it so that your putty, be it green stuff, milliput or whatever, doesn't stick to the mould itself? I've had pretty good results with talcum powder thus far on the odd occasion I've delved into this area, but I wondered if any of you out there have some slightly more elegant solutions or just something that works for you.

Have at it, thanks in advance.

I used Vaseline making green stuff moulds

I haven't had to use anything when using instant mould and greenstuff, it's always just come out fine. That's the nice thing about instant mould, it doesn't really need mould release agents.

But I do find I only get maybe half a dozen casts per mould and I can only reuse the instant mould to make maybe half a dozen moulds before it loses its non-stick properties... at which time I just buy more, lol.

Instamold is amazing!!! It has a millionty other uses too!

A.S.S: I will happily take all of your "spent" Instamold. I've been making Lovecraftian sculptures out of it.

Vegetable Oil does a good enough job, you just need to give the component a good wash before painting.

If you are using Instant Mould (if that's the stuff that deforms with heat), can't you just submerge it in hot water again and just pull it away from the moulded part?

Automatically Appended Next Post:
@Paradigm: you can, but then it's a one-shot deal.

I've used Vaseline (or generic petroleum jelly) diluted with baby oil. I don't have a set proportion; I eyeball it until it is thin enough to brush onto the mold with a cheap paintbrush. I dilute because when I use too much jelly, it sometimes obscures details in the casting.

I don't always use the Vaseline, but when I do, I found that it increases the number of castings I get out of a mold. In my part of the world, a tub of Vaseline is way cheaper than mold making supplies.

Using warm, instead of hot, water on the mold with the casting in it can soften the mold enough to release the casting, without deforming the mold too much. But I prefer using my Vaseline over risking deforming a mold.

When using oyumaru (or instant mold) you shouldnt need to use a mold release agent for greenstuff/milliput. The stuff is non stick. (I was under the impressions that this, along with reusability was basically why its good?)

@HairySticks - You are correct, for the first several castings the instant mold stuff, a mold release agent isn't necessary. However, ALL molds (instant or otherwise) have a lifespan and wear out with repeated castings, regardless if they are marketed as "reusable" or "no mold release necessary." I've observed that molds made from an original with negative space wear out quicker. Also, instant molds wear out quicker than "not instant" molds (ie 2 part RTV silicone). In regards to failed casts, I've had pieces with skinny bits (blades, staves, spikes) break off during the demolding process. (Though disheartening, it can often be fixed with CA glue. Even if it can't be fixed, it can still be an effective bit given the right weathering techniques when painting, or used as diorama battle debris). When the non-stick properties begin to wear out (after several castings), or when my piece is skinny, that is when I begin considering the Vaseline.

That being said, I've never used the "oyumaru" that you mentioned. Is it a brand, or a type of instant mold? Do you like it? Is it expensive? Do you get it in stores or on the internet? How many castings can you get out of a mold? If you've had success with it, I may check it out.

Honestly, I've turned away from instant mold products for the time being, partly because of the issues mentioned by the OP. In my town, there is an art school which has spawned lots of art supplies stores - some of these sell RTV silicone (not instant mold, takes half a week to make a two part mold) at prices cheaper than the internet. While start up costs and learning curve can be significant, here it is cheaper mold for mold and cast for cast than the instant mold + epoxy method.

Oyamaru = instamold/instamorph for the most part, it's just cheaper because it's not marked up for nerds.

I've found that milliput will stick a bit to a two-part mold of the stuff, but press molds are hassle free. Just wait for it all to set, then use a dab of superglue and a stick or something to pull the piece out (if you can't just pop it out no probs or using a knife).

Instant mould is not suitable for long term usage as a mould you can get a number of press moulds before you need to heat it up and re-use/make the press mould again. Te only lubrication you should ever use with instant mould is water. If your finding the material is degrading it will be down to your using lubrication that's not needed.

I've replaced a missing dragon arm with instant mould:


Press moulding I've used plenty to add skulls/body bits to bases etc. This lot were produced in a night with a single press mould of each different body part and only using water lubrication:


If you want multiple copes of a single mould then you need to upgrade to a pour in mould made with rubber. As long as you don't have any major undercuts the mould should last many many castings. I've got moulds of bases I made years ago still producing quality casts.

These are just some of my bases:

 MadDokMathWych wrote:
@HairySticks - You are correct, for the first several castings the instant mold stuff, a mold release agent isn't necessary. However, ALL molds (instant or otherwise) have a lifespan and wear out with repeated castings, regardless if they are marketed as "reusable" or "no mold release necessary." I've observed that molds made from an original with negative space wear out quicker. Also, instant molds wear out quicker than "not instant" molds (ie 2 part RTV silicone). In regards to failed casts, I've had pieces with skinny bits (blades, staves, spikes) break off during the demolding process. (Though disheartening, it can often be fixed with CA glue. Even if it can't be fixed, it can still be an effective bit given the right weathering techniques when painting, or used as diorama battle debris). When the non-stick properties begin to wear out (after several castings), or when my piece is skinny, that is when I begin considering the Vaseline.

That being said, I've never used the "oyumaru" that you mentioned. Is it a brand, or a type of instant mold? Do you like it? Is it expensive? Do you get it in stores or on the internet? How many castings can you get out of a mold? If you've had success with it, I may check it out.

Honestly, I've turned away from instant mold products for the time being, partly because of the issues mentioned by the OP. In my town, there is an art school which has spawned lots of art supplies stores - some of these sell RTV silicone (not instant mold, takes half a week to make a two part mold) at prices cheaper than the internet. While start up costs and learning curve can be significant, here it is cheaper mold for mold and cast for cast than the instant mold + epoxy method.

When I first looked at instant mold, it became apparent that its re-branded 'Oyumaru' a Japanese craft item. Even imported, its cheaper and available in many colours.
Identical product really. Price difference may not be worth it on small amounts. I got 40odd sticks and it was worth it.
http://www.ebay.co.uk/itm/Oyumaru-modeling-Compound-Moulding-Stick-Clear-12pcs-set-/231356647299?_trksid=p2141725.m3641.l6393 heres an example of the brand, its logo and packaging from an ebay seller ~ youd prob get 10 sticks of instant mold for the price of this 12 Oyumaru.


Which ever you buy, I've never found a need for any mold release with oyumaru, I've been using the same bunch of sticks for over 24months. many many casts and remoldings.
simple 1 part molds and more complex 2 part molds.
If you let the putty cure, it will not stick. Simple as that. I dont think age of product has anything to do with it. Just patience for demolding. - someone posted a photo of a bunch of parts they did in an evening up there somewhere; I cant go that fast. You must be demolding before the putty is cured? What putty? greenstuff / milliput your talking 1 or 2 casts per evening per mold. tops. Simply due to the cure time.



I had wondered about pouring resin into oyumaru.. anyone tried that? the exotherm of the resin concerned me.. would your average resin really get hot enough to reform the mold?

@HairySticks - The trick to speed production with the above is making a stamp which has zero undercuts so there's nothing to pull at the piece your stamping out. Then work out how big a ball of gs is required to just over fill the stamp and then place multiple blobs of gs onto a thin piece of plasticard and stamp away dipping the stamp in water on a regular basis. The gs sticks to the plasticard but due to the water and none stick properties of the instant mould it doesn't stick to the stamp. Lift off the stamp after pressing firmly and you end up with a gs skull or whatever you have decided to make. Leave the gs to cure on the plasticard and then once cured flexi the plasticard and the gs will pop off.

@SW1 and @HairySticks - Thanks for the info! Very helpful.

@HairySticks, re: exothermic reaction - Using the product called Smooth Cast 300, it gets very hot once mixed - I've never used a thermometer, but it is painfully hot to my fingertips, while the hot water is only uncomfortably hot. Also, don't touch the stuff with your fingers, because in addition to being hot, it causes cancer in the state of California. (Not sure if this means that it doesn't cause cancer in the UK? )

Lol ... Resin won't go into instant mould as it gets too hot and the instant mould deforms.Tried and got a messy result.

What about a slower curing resin? The slower the cure typically the less heat is released. Or maybe leave it in the frig before mixing it and pouring it? The reaction is both exothermic and also sped up by heat, if you cool it down then it'll react slower and less heat will be released.

AllSeeingSkink wrote:
What about a slower curing resin? The slower the cure typically the less heat is released. Or maybe leave it in the frig before mixing it and pouring it? The reaction is both exothermic and also sped up by heat, if you cool it down then it'll react slower and less heat will be released.

You need a certain minimum temp for the reaction to occur properly. Too low and you get brittle resin. Don't chill the chemicals before casting.

SW1 wrote:
Resin won't go into instant mould as it gets too hot and the instant mould deforms.Tried and got a messy result.

I use quick cast resin (15 minute cure time) with my instant mold all the time. I only have one pack of instant mold though, the rest is oyumaru branded instant mold because it is way cheaper. I haven't had it deform my molds. They were however one piece molds and not two piece. For my two piece molds I do a green stuff press... otherwise I use Smooth-On silicone to make a real two piece mold when needing production pieces.

 Dark Severance wrote:

SW1 wrote:
Resin won't go into instant mould as it gets too hot and the instant mould deforms.Tried and got a messy result.

I use quick cast resin (15 minute cure time) with my instant mold all the time. I only have one pack of instant mold though, the rest is oyumaru branded instant mold because it is way cheaper. I haven't had it deform my molds. They were however one piece molds and not two piece. For my two piece molds I do a green stuff press... otherwise I use Smooth-On silicone to make a real two piece mold when needing production pieces.

Interesting. What brand of resin do you use?

SW1 wrote:
Interesting. What brand of resin do you use?

I normally and prefer to use Smooth-On, the type depends on what I want. They have a base liquid plastic/resin that I use but I also use their high impact resin which is more like plastic. They do have a longer cure time about 1 1/2 hours. Unfortunately they aren't local and I have to order it so I have to rely on local supplies to not eat into my production supplies.

For quick casts, since it only takes 15 minutes to cure I use TAP Plastic Quick Cast. I use it for when I need to do quick and test casts or to create a production piece, which I'll later make a 2 part silicone mold for. I use it because I can pick it up locally and its fast cure time. I've used it when creating new base designs, using the Oyumaru to create a one piece mold with a flat bottom (using the lego method). Then I can pour the resin from the top, it pops out easily and then sand the 'extra' layer on the bottom smooth. Then I can take that if I like it to create a production cast, usually a 2 part silicone mold. The other nice thing because of the fast cure time, if you pull it slightly early the resin is very pliable and soft. It lets me take flat pieces to create curved parts or add in minor details like 'battle damage' as well as trimming excess.

... Okay, I have a lot of press molding experience here, and I have to say instant mold absolutely does not stick to green stuff. I think you are not letting it dry long enough. Let it sit for at least 24 hours (TBH I live in a warm area and 12 hours is usually plenty) and start at one end of the mold and lift, and it should come right out.


Automatically Appended Next Post:
Talcum is only needed if you're using something like polymer clay. You're probably ruining your instant mold by using release agents when they're not using at all.

SW1 wrote:

AllSeeingSkink wrote:
What about a slower curing resin? The slower the cure typically the less heat is released. Or maybe leave it in the frig before mixing it and pouring it? The reaction is both exothermic and also sped up by heat, if you cool it down then it'll react slower and less heat will be released.

You need a certain minimum temp for the reaction to occur properly. Too low and you get brittle resin. Don't chill the chemicals before casting.

I guess just use a slower resin then?

If the piece I'm copying has overhangs or tons of tiny details, I'll use canola spray, which I also use when working with greenstuff. But yes, greenstuff shouldn't stick to your mold, it's just a precaution.