Resin Alternatives for Small Molds

[peteski]

I use Bondic a lot for small parts and no mold release is required. It is advertised as a "glue" but it hardly sticks to anything.

That is the funny part - in commercials they use it to bond things together, but their website is http://notaglue.com/ and the FAQs on that site also mention that fact several times.

[peteski]

I have also never used any resin which doesn't have a 1:1 mix ratio. I buy the smallest possible size kits but I still wish that they made even smaller resin sets available for purchase because I do end up throwing some away.  I use the "extend" gas blanket and keep it in cool place, but the moisture still gets in the resin.

[talon63]

I occasionally have to make a small mold (think emblems and things of that nature) out of either foil or common silicone sealer. Not wanting to mess with resin, I've had luck filling such small molds with J-B weld, common epoxy, and even carpenter's sandable wood glue (cures harder than common Elmer's, but requires several thin layers over several days). Now I'm interested in doing some larger parts (specifically, rocker panels for C2 Corvettes). Been wondering if something else might work better for these. How about hot glue? What about melting styrene sprue in something like a large spoon and pouring that in? Has anyone tried either of these materials to make small parts?

And before someone says "Just use resin," let me reiterate that I'm looking for ALTERNATIVES to resin. I don't want to get into resin for various reasons if there's any way to avoid working with the stuff.

How about hot glue? - too flexible, might be good for tires, but as a casting agent, doesn't "cure" hard enough for most applications. Also doesn't detail out well on larger casts, unless you can up the pressure to make it really inject into the mold.

What about melting styrene sprue in something like a large spoon and pouring that in? I use a very small BBQ Sauce pot made of stainless steel and a Candle warmer. Candle warmer surface temp breaks 300 degrees f. Melts most plastics beautifully, just don't let it sit too long, it will develop air bubbles. You can reach a pretty liquid consistency and either pour from the pot or inject small amounts with a syringe. Clean up is fairly easy, let the melted material set up again and pops out of the melting pot, and even out of the syringe body with very little effort. For very small amounts of casting material I make a crucible out of tin foil, melt what I need, and toss it when I'm done.

I've played with those melting beads that dioramists use to make water.  (Woodland Scenics E-Z Water) It melts quickly, dries plenty hard and can be done in very small amounts. Also, it's mostly clear. 

There's also a plastic medium that you are supposed to put in hot water, when it turns clear you mold it, and let it sit until it turns white again. (UtilePlast) Lower melting point than sprue. I just melt it without the water, using the candle warmer method. Fill the mold and when it turns white, pop it out. Pretty good results with it, not as hard as the "water" beads mentioned above, but harder than hot glue when cured.

Finally, I just started playing with a 3Doodler, 3D pen as a mold "injector". First attempts on very small parts are promising and PLA is cheap enough. Largest mold I've attempted so far is a transmission in two halves. Not that pretty, but better than a hot glue gun due to the forced feed of the 3D pen. Emblems come out OK, but may require a bit of trimming depending on heavy handed you are in filling the mold.

 

Edited December 28, 2016 by talon63

[Snake45]

How about hot glue? - too flexible, might be good for tires, but as a casting agent, doesn't "cure" hard enough for most applications. Also doesn't detail out well on larger casts, unless you can up the pressure to make it really inject into the mold.

What about melting styrene sprue in something like a large spoon and pouring that in? I use a very small BBQ Sauce pot made of stainless steel and a Candle warmer. Candle warmer surface temp breaks 300 degrees f. Melts most plastics beautifully, just don't let it sit too long, it will develop air bubbles. You can reach a pretty liquid consistency and either pour from the pot or inject small amounts with a syringe. Clean up is fairly easy, let the melted material set up again and pops out of the melting pot, and even out of the syringe body with very little effort. For very small amounts of casting material I make a crucible out of tin foil, melt what I need, and toss it when I'm done.

I've played with those melting beads that dioramists use to make water. It melts quickly, dries plenty hard and can be done in very small amounts. Also, it's mostly clear. 

There's also a plastic medium that you are supposed to put in hot water, when it turns clear you mold it, and let it sit until it turns white again. Lower melting point than sprue. I just melt it without the water, using the candle warmer method. Fill the mold and when it turns white, pop it out. Pretty good results with it, not as hard as the "water" beads mentioned above, but harder than hot glue when cured.

Finally, I just started playing with a 3Doodler, 3D pen as a mold "injector". First attempts on very small parts are promising and PLA is cheap enough. Largest mold I've attempted so far is a transmission in two halves. Not that pretty, but better than a hot glue gun due to the forced feed of the 3D pen. Emblems come out OK, but may require a bit of trimming depending on heavy handed you are in filling the mold.

Excellent! This is EXACTLY the kind of information I'm looking for! Thanks so much!

[Ace-Garageguy]

Excellent! This is EXACTLY the kind of information I'm looking for! Thanks so much!

Agreed. Lots of interesting ideas certainly worth further investigation.

[talon63]

Glad I could help. I should probably try to post pics of some of the successes and failures I've had, along with how they were done. May prove useful to some to avoid some of the problems I've run into.

[426-Hemi]

I'ma Resin molder, and as well have done plastic injection modeling spin casting with metals, and so far, I like the resin useage BUT you have to store it properly and then as said air bubbles seem to be the worst part of it.... Waste, YES, MY GOD YES, if you mix more then you have out in molds you have to pour fast (that is what creates a lot of the air bubbles is pouring fast, BUT to not "waste" it is another whole issue!

I however being a resin molder, am open to other things for the same use! 

Allen, I LOVE some of the ideas, what about the hot glue? it comes out like a gel from a glue gun, but what about turning up the heat on it to literally liquefy it? Not as much as water, BUT if we as molders could find SOMETHING that is liquid like water, would very well fill our molds MUCH better.... AND show a LOT more detail too!

I'm gonna toy with that liquid epoxy coating you put onto restaurant table tops and even bars. it covers like 60 coats of polyurethane does, BUT is epoxy..... takes 24 hours to dry, and it mixes 1:1 by weight, and if dome right, it dried CLEAR.... I've used it for making "water" for some of my Wife's Diorama's in the past to be "water".... for her Whimsical creations....and years later that same thing looks clear as water, dried smooth, and can be "sculpted", if you catch it at the right time, but when mixed, this stuff is like real "water" it finds its own level..... can be painted, and glued too. So theres an idea! Takes a bit for it to fully cure tho, after 24 hours it can and will still "fingerprint"!!!

Some of whats been said here, I myself am gonna look further into. ALL sounds like some REALLY good ideas!

 

[426-Hemi]

Snake,

That Permatex black silicone will it stick to say a car body or anything? I wouldn't mind trying that for some car body parts that are there that I really do NOT wanna destroy the car just to mold parts off of it!

[talon63]

Allen, I LOVE some of the ideas, what about the hot glue? it comes out like a gel from a glue gun, but what about turning up the heat on it to literally liquefy it? Not as much as water, BUT if we as molders could find SOMETHING that is liquid like water, would very well fill our molds MUCH better.... AND show a LOT more detail too!

I'm gonna toy with that liquid epoxy coating you put onto restaurant table tops and even bars. it covers like 60 coats of polyurethane does, BUT is epoxy..... takes 24 hours to dry, and it mixes 1:1 by weight, and if dome right, it dried CLEAR.... I've used it for making "water" for some of my Wife's Diorama's in the past to be "water".... for her Whimsical creations....and years later that same thing looks clear as water, dried smooth, and can be "sculpted", if you catch it at the right time, but when mixed, this stuff is like real "water" it finds its own level..... can be painted, and glued too. So theres an idea! Takes a bit for it to fully cure tho, after 24 hours it can and will still "fingerprint"!!!

The hot glue gun I have on hand is about the cheapest one you could get. Temp isn't really adjustable, however, using the candle warmer and a small tinfoil cup, you might get it to the a pourable consistency, probably not like water, but at least more honey like than what you get from a cheap hot glue gun.

That liquid epoxy might be useful, may even be the same as stuff marketed as floor leveler. It will flow almost as well as water, closer to warm syrup, but it is self leveling, and dries clear or with a slight yellowish tinge. Biggest draw back is still going to be dry time. Like the OP, I was trying for more immediate use results than something that will take a quarter hour to 2 days to be useful. Even if my idea is a flop, I'd rather know pretty quickly than wait for a long to find out I have to start over. 

Snake,

That Permatex black silicone will it stick to say a car body or anything? I wouldn't mind trying that for some car body parts that are there that I really do NOT wanna destroy the car just to mold parts off of it!

I use siliconized acrylic and 100% pure silicon caulk to make small molds, like car batteries and various other bits and bobs. I've even cast painted pieces (rattle can painted and brush painted), and with a little care, you can demold an object without damaging it or the mold if you work slowly to release it. Even the paint remained unharmed in my tests. (Your mileage may vary, and while I've not experienced any interactions with the paints already on the pieces, I haven't tested against that many brands or types of paint and no lacquers. 

 I haven't tried it on things with a lot of angular complexity, like over/under hangs, deep recesses or the like. The detail on a battery top is well defined. Again, the biggest issue is dry time, but it's usually not too bad for small pieces. I'd say as long as your original is clean, you shouldn't have an issue getting the silicon off, it should almost peel away with minimal work, based on my experience thus far.

[426-Hemi]

The hot glue gun I have on hand is about the cheapest one you could get. Temp isn't really adjustable, however, using the candle warmer and a small tinfoil cup, you might get it to the a pourable consistency, probably not like water, but at least more honey like than what you get from a cheap hot glue gun.

That liquid epoxy might be useful, may even be the same as stuff marketed as floor leveler. It will flow almost as well as water, closer to warm syrup, but it is self leveling, and dries clear or with a slight yellowish tinge. Biggest draw back is still going to be dry time. Like the OP, I was trying for more immediate use results than something that will take a quarter hour to 2 days to be useful. Even if my idea is a flop, I'd rather know pretty quickly than wait for a long to find out I have to start over. 

I use siliconized acrylic and 100% pure silicon caulk to make small molds, like car batteries and various other bits and bobs. I've even cast painted pieces (rattle can painted and brush painted), and with a little care, you can demold an object without damaging it or the mold if you work slowly to release it. Even the paint remained unharmed in my tests. (Your mileage may vary, and while I've not experienced any interactions with the paints already on the pieces, I haven't tested against that many brands or types of paint and no lacquers. 

 I haven't tried it on things with a lot of angular complexity, like over/under hangs, deep recesses or the like. The detail on a battery top is well defined. Again, the biggest issue is dry time, but it's usually not too bad for small pieces. I'd say as long as your original is clean, you shouldn't have an issue getting the silicon off, it should almost peel away with minimal work, based on my experience thus far.

Yeah, I wasn't clear enough When I mentioned turning up the heat, I meant to use a different Heat source! I know most glue guns don't come with temp controls! At least not El Cheapo's anyway I had one of the more refined (AND expensive glue guns about $180 worth) till it got stolen a long time ago... I know the Felon that did it too! LOL  

But to use some sort of flame, or other heat source that get hotter then the common glue gun may be a trick to attempt! HMMMM

I want to mold a set of '70 Dodge Charger side scoops that have the "R/T" emblem as part of the model for another use, BUT, I don't want to ruin the car body to do so.... I don't think the body is painted, (maybe) But the paint isn't an issue as its a glue-bomb rebuilder, in half ways decent shape (or at least the body it, the frame and interior are a whole OTHER story, but I think a common '69 frame and interior from MPC would replace it quite easily, but I want to use those side scoops on another build if I can, I'm just not sure on type of silicone to use that won't stick to the plastic and run both the body of the car, and those side scoops! BUT, that too I also want them molded to use on another build and maybe make a mold to pass along to others in trades.... 

[Snake45]

Snake,

That Permatex black silicone will it stick to say a car body or anything? I wouldn't mind trying that for some car body parts that are there that I really do NOT wanna destroy the car just to mold parts off of it!

I've never had any problems. I put it on, let it cure 24 hours (or 24 hours per layer--sometimes I use two or more), and then just peel it right off. Get a tube and experiment with it yourself before committing to a rare body if you have doubts.

[talon63]

 

 

But to use some sort of flame, or other heat source that get hotter then the common glue gun may be a trick to attempt! HMMMM

.. 

Biggest concern there, as stated previously, is that when the hot glue sets, it's pretty flexible. It really would make a better tire than it would body panels. for the emblems themselves it might work, but so far my best results have come from the 3Doodler pen, the UtilePlast, and Woodland Scenics E-Z Water.

I have used hot glue to make a one-shot mold, but the original was metal. I'd be leary of using it on styrene to make a mold, since the heat may be enough to damage the original. Also, the waxiness of the hot glue, even after curing, makes it harder to attach to other things without more specialized adhesives.

Here's an example of casting with hot glue, straight from the el cheapo glue gun. Huge loss of detail because the flow is horrible. The mold was made with Air Dry clay, which captures the details well, but I can't really suggest it for mold making. Drying time is long, although shrinkage isn't bad, but you may only get one cast from it, and depending on what you cast in it, it may bond and require a lot of cleanup of the copy.

This one is actually made up of several parts and, when finished, is going into a diorama as part of a junker. It has a few more layers of grunge to go, and a few parts to add.

Edited December 28, 2016 by talon63

[426-Hemi]

I've never had any problems. I put it on, let it cure 24 hours (or 24 hours per layer--sometimes I use two or more), and then just peel it right off. Get a tube and experiment with it yourself before committing to a rare body if you have doubts.

THANKS man, thats just what I'll do, try it out on say a old body (common one) on say a door handle, and see how it goes!!!! BEFORE I go and try it to a rare body.....

[Ace-Garageguy]

...I have used hot glue to make a one-shot mold, but the original was metal. I'd be leary of using it on styrene to make a mold, since the heat may be enough to damage the original...

 

Bingo.

I HAVE used hot-glue in several attempts to mock-up styrene parts (I use hot glue constantly in my real-car work and find it to be invaluable) and the normal-sized glue-guns produce a stream of adhesive that WILL melt styrene, becoming permanently attached to the parts.

I have been getting around to trying the very small "craft" glue guns that use much smaller glue sticks (and I assume, operate at lower temperatures).

[talon63]

I think even the "craft" guns get above 117-120 degrees, which is enough to damage styrene. The one I tested was a craft type gun, about 5 bucks. 

[Snake45]

I think even the "craft" guns get above 117-120 degrees, which is enough to damage styrene. The one I tested was a craft type gun, about 5 bucks.

120 degrees won't damage styrene. I have a bunch of kits that were stored in an attic that would get to that temp, and they're all fine. Also, the hot water in my house is at least 140 and I hold styrene under that when I'm trying to un-warp something, and it still takes a bit of effort to get any effect.

Besides, I'm not going to put the hot glue on styrene, I would be putting it into either a silicone or a foil mold.

[gtx6970]

Interesting, Info. I never would have thought to use  hot glue as a filler material

Here  is MY prime example of a small molding idea  -  I have a conversion coming close to the top of the pile. I want to convert a Johan 61 New Yorker kit I have with the roof cut off of it into a 1961 Chrysler 300 convertible. Using the Johan 1962 300 as a parts donor

I want to pull a mold off the 62 300 kits side emblems and transfer them to my 61 body.  Ive done the clay impression idea and IMO the emblem is to shallow to work with successfully.  

Now I can try using cheap kitchen foil, or BMF with the adhesive cleaned off. Then the clay to hold it in shape and just fill the backside of the foil with hot glue . Once the glue is set up, remove it from the clay and trim as required. then superglue it to the 61 body.  Sure sounds like a good idea to me

 

If it works , I may try to pull molds from the New Yorker emblems and transfer to them the 62 kit and make a New Yorker hardtop

[Snake45]

Interesting, Info. I never would have thought to use  hot glue as a filler material

Here  is MY prime example of a small molding idea  -  I have a conversion coming close to the top of the pile. I want to convert a Johan 61 New Yorker kit I have with the roof cut off of it into a 1961 Chrysler 300 convertible. Using the Johan 1962 300 as a parts donor

I want to pull a mold off the 62 300 kits side emblems and transfer them to my 61 body.  Ive done the clay impression idea and IMO the emblem is to shallow to work with successfully.

Now I can try using cheap kitchen foil, or BMF with the adhesive cleaned off. Then the clay to hold it in shape and just fill the backside of the foil with hot glue . Once the glue is set up, remove it from the clay and trim as required. then superglue it to the 61 body.  Sure sounds like a good idea to me

 

If it works , I may try to pull molds from the New Yorker emblems and transfer to them the 62 kit and make a New Yorker hardtop

You've got the idea exactly. Don't mess with cleaning off BMF, just use cheap kitchen foil. A toothpick will work it into EVERY nook and cranny and get all the detail. Then back it with clay or silly putty and pull it off the car. For something like this, I'd just fill it with superglue or the carpenter's glue, I wouldn't mess with hot glue on something that small. TIP: Make several while you're at it--six or eight. Won't be that much more work once you're set up to do it. Then you can pick the best two to use on your model.

[Mark]

I've never seen hot glue cause damage to styrene.  I've used it to temporarily attach Jimmy Flintstone resin bodies to donor chassis, applying it along the inside of the body to pull the sides back to the proper shape. 

Often the JF bodies are pulled off of the molds before the resin has fully set, and that causes the body sides to bow outwards a bit.  When I'd get one of those bodies, I'd compare it to the body from the donor kit and, more often than not, the rocker panels would be further apart on the resin body.  Clean up the inside of the resin body, stick the interior in (and other parts like the firewall if you think that will be helpful), and hot glue the body to the chassis in the same relationship as if you were using the kit body.  Throw it into the box, when you get back to it and take it apart the body should hold the correct shape from then on.  The glue method pulls the body into its intended shape, and also fixes other issues like hood fit which can be thrown off by the lower body distortion.  If you do this with, say, rubber bands around the body, that could cause other problems like pulling the roof down.  The rubber bands often dry out and fall apart too.

[Snake45]

I've never seen hot glue cause damage to styrene.  I've used it to temporarily attach Jimmy Flintstone resin bodies to donor chassis, applying it along the inside of the body to pull the sides back to the proper shape.

Often the JF bodies are pulled off of the molds before the resin has fully set, and that causes the body sides to bow outwards a bit.  When I'd get one of those bodies, I'd compare it to the body from the donor kit and, more often than not, the rocker panels would be further apart on the resin body.  Clean up the inside of the resin body, stick the interior in (and other parts like the firewall if you think that will be helpful), and hot glue the body to the chassis in the same relationship as if you were using the kit body.  Throw it into the box, when you get back to it and take it apart the body should hold the correct shape from then on.  The glue method pulls the body into its intended shape, and also fixes other issues like hood fit which can be thrown off by the lower body distortion.  If you do this with, say, rubber bands around the body, that could cause other problems like pulling the roof down.  The rubber bands often dry out and fall apart too.

VERY interesting! I have a couple of JF bodies so afflicted.

[ChrisBcritter]

Interesting, Info. I never would have thought to use  hot glue as a filler material

Here  is MY prime example of a small molding idea  -  I have a conversion coming close to the top of the pile. I want to convert a Johan 61 New Yorker kit I have with the roof cut off of it into a 1961 Chrysler 300 convertible. Using the Johan 1962 300 as a parts donor

I want to pull a mold off the 62 300 kits side emblems and transfer them to my 61 body.  Ive done the clay impression idea and IMO the emblem is to shallow to work with successfully.  

Now I can try using cheap kitchen foil, or BMF with the adhesive cleaned off. Then the clay to hold it in shape and just fill the backside of the foil with hot glue . Once the glue is set up, remove it from the clay and trim as required. then superglue it to the 61 body.  Sure sounds like a good idea to me

 

If it works , I may try to pull molds from the New Yorker emblems and transfer to them the 62 kit and make a New Yorker hardtop

I've done this with foil and Bondic - made copies of '58 Ford side trim for my custom '56 Plymouth. Works quite well.

[Mike Chernecki]

Well I bought a tube of Permatex Black silicone and did a few tests. Everything I applied it to, it become one with the part, impossible to remove with destroying the part and the silicone mold. I even tried cover parts in Baremetal foil first, it saves the original part, but the foil cannot be removed from the mold rendering it useless.

[Mark]

VERY interesting! I have a couple of JF bodies so afflicted.

I just checked a couple of JF bodies that are packed away.  The '51 Chevy sedan delivery is still stuck together with the hot glue...and the kit hood fits the body as good as it fits the original kit body.  It has the kit firewall, interior platform, and chassis in it.  The upper part of the floor (behind the rear seat) has been cut in preparation for building the load floor in the back.  Prior to gluing it up to pull the body sides in, the hood didn't fit worth a darn. 

The '53 Studebaker phantom sedan delivery is also still stuck together with the interior and chassis.  That one didn't have any problems with hood fit, but the lower body sides were splayed outward a bit.  I've got to figure out just how I want to do the interior for that one.

I've also got a pre-chopped Studebaker salt flats body that got the rubber band treatment.  One of the rubber bands fell apart and the other one dried out (from not even three years ago; I bought all of these at NNL East over the years).  But the body is pulled into the correct shape and has stayed that way.  This body has the pre-chopped top piece built into it; I've got to tweak that because the kit windows don't really fit that top very well. 

[talon63]

Well I bought a tube of Permatex Black silicone and did a few tests. Everything I applied it to, it become one with the part, impossible to remove with destroying the part and the silicone mold. I even tried cover parts in Baremetal foil first, it saves the original part, but the foil cannot be removed from the mold rendering it useless.

You may have to apply what seems like a lot of silicone to have enough "body" to allow easy peel off when it sets. Most of my silicon molds are between 1/4" to 1/2" thick, even more for larger pieces. That gives enough strength to remove with out damaging the mold, and working slowly, should peel off the source material with minimal work. 

[Mike Chernecki]

You may have to apply what seems like a lot of silicone to have enough "body" to allow easy peel off when it sets. Most of my silicon molds are between 1/4" to 1/2" thick, even more for larger pieces. That gives enough strength to remove with out damaging the mold, and working slowly, should peel off the source material with minimal work. 

I did one where the silicone was nearly 1/2" thick and the main body of the silicone was undamaged, but the surface attached to part I want to make a mold of shredded while trying to peel it off. There are still bits of silicone embedded in the details on the surface of the part.