How To Cut Silicone Molds For Production Resin Casting

In this video I cover how to cut open silicone rubber molds for casting hundreds of copies in urethane resin.
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Check out Crazy Al Evans on his website. www.tikimania.com
and his KZbin Channel. / crazyalevans .
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[@RobertTolone]

Here is a link to a downloadable PDF file with a list of the rubber, resins and waxes I use in my videos: www.dropbox.com/s/kz6mhmf7v5vpy7l/Material%20and%20Suppliers.pdf?dl=0

[@bryansiepert9222]

Ever since the first video of yours I saw, I've "seen the light" on cut/single part molds. Perhaps more importantly, the emphasis you put on the mechanics of making and using a mold are extremely valuable. I always had an inkling that how and where the bands apply pressure was important, but you really made it clear. Thanks!

[@Tanahmera]

I am so happy I found your channel before I started my resin journey. Thank you for taking the time to teach how to do things properly.

[@gawni1612]

You're a born entertainer, and a master craftsman, Robert! Keep it up!

[@cathb6401]

Great videos. Mold making has always been intimidating, now I am inspired to give it a try. Thank you.

[@Ralphl100]

Excellent instruction!

[@Declan-pg8cg]

I absolutely agree; relatively small molds work better with experienced clean cuts, as opposed to claying up for multi-part molds. Some require it, but definitely not most. I'm working on a 3 foot long humpback that will only require a glove mold and minor cut. I love your practical and no nonsense approach. Keep up the good work.

[@melissal7984]

I wish that I could give you a big hug! Thank-you for this video!!

[@rohangoldswain7263]

Really great tutorial!

[@IgnaCosplay]

Thank you so much for this video. I really didnt want to do a two part mold because i hate the waste of time so i try just to cut of the mold i made and was just perfect. Seriously thank you for your words.

[@susiekelly5763]

I love your channel! Very well done & informative, no bs which is nice !

[@RobertTolone]

Thanks for watching Sooz Q!

[@yzspring]

Sir..just wanna say you have really informative channel here👍

[@RobertTolone]

Glad you enjoyed it, thanks for watching!

[@potatoefacedfox]

very informative and great help, thank you

[@RobertTolone]

Thanks so much for watching!

[@5t66t5]

"Use a WICKED sharp Exacto Blade" You must be from Boston. Fantastic videos that are endlessly helpful.

[@RobertTolone]

Not from Boston, but I’ve been there a few times. I went there to see the Fairfield Porter retrospective at the MFA. Thanks for watching my videos!

[@dianeharris2687]

Look forward to seeing you work with other people's projects. I will probably never do mold making, but I find the process and problem solving very interesting. Plus in some far-away alternate reality, it's like I'm in the studio with you.

[@RobertTolone]

Well, maybe you could design pieces for your jewelry that we could cast...

[@liliangel3551]

Thank you so much :)

[@mrc8308]

Great video!

[@RobertTolone]

Thanks!

[@treblam1]

WOW!! SHAZAM!

[@rrswitch48]

OMG I'm the 36 hour guy you mentioned claying-up. Nice lesson!

[@RobertTolone]

😄

[@user-gk9ut9qc1o]

You are very right, sir! I hate clay moulds too, they are over engineered. I like your videos :)

[@TheGraveDiggersWorkshop]

Wonder if youve ever considered doing a molding and casting video on the expanding rubber molds? I seen the "brick int he yard" page,they have some molding material that expands in water.

[@kamarte]

I recently got to know your channel and should say it is very professional and well produced with plenty of quality contents. But regarding selection of type of mold and specially clay two-half molds, I would like to mention that type of mold really depends on geometry of prototype. For a complex piece like one you did, your molding type and method impeccable. However, for simple shapes with a straight parting line, I for one would opt for a clay molding. I do started to watch as much of your videos and like your jobs. Thanks !

[@RobertTolone]

Absolutely right! Check out these videos: kzbin.info/www/bejne/rXWviJSNj9yBo5o kzbin.info/www/bejne/bWe3gp2kp5hmmJI

[@johnkelley9877]

This was very helpful and it explained a lot about making cuts in molds. I plan on using this technique on my scratch built models. Thanks for sharing this information.

[@RobertTolone]

Glad you found it helpful John

[@Nickporter17]

Perfecto 👌

[@RobertTolone]

👍

[@floflocraftcorner3552]

Trying to make a funky pop mold to make as a gift to make it clear how do you do the head and body

[@adrianacruz6177]

Thank you so much.Finally i understand how sprues work.I was wondering how you cut the pipe in the half to make the containment box. And this silicon that you use is a tin one. And of what shore you recomend to do it . To avoid to be deformed. 🤗

[@RobertTolone]

I cut the plastic pipe with a tablesaw, but a band saw or hand held saw would cut it too. The rubber is a tin based silicone Shore A 25. It is soft and flexible. Close the mold with as little pressure possible to avoid deforming it.

[@adrianacruz6177]

@@RobertTolone Thank you so much. 💗Im going to try to make a mold with your tecniques. It will be awsome . 🌺

[@stephenmatusek1583]

Bob I'm ready to try to make my first mold and I'd heckum love to send progress shots

[@RobertTolone]

Send pics to [e-mail]

[@shanewolf71]

Hey I have a design that’s been giving me trouble, it has handcuffs and shackles which is tricky with cutting through the mold removal. 6 inch bear figurine. I’ve went through at least 4-5 molds. I have the prototype. Hopefully you can give advice or give it a try?

[@tb-croix22]

Hey Robert, I’ve got a project I’ve made for my son. It’s a LEGO brachiosaurus. I’ve sculpted it in Autodesk 3ds Max and 3D printed it using a SLA resin printer. I’ve been watching your videos non-stop for months trying to get prepped to do a casting of it….SLA resin is just too brittle for regular play. There are 22 major parts that make up the dinosaur plus 5 unique small parts that provide the articulation. Let me know if this would be something you’d be interested in making a series of videos on. Thanks!

[@RobertTolone]

Hi Thom, send some pics to me at [e-mail]. Thanks.

[@wasthereshiny]

Hi Robert! Thank you for the video. You say that this process is quick and easy, but you also say that it's tricky and needs a lot of experience to get right. As someone who is attempting to make a mold for the first time (with Smooth on Mold Star 30, original is a real crab leg), would you recommend this technique, or a clay mold? Thank you!

[@monodo56]

M.E. Francis Both methods work. Both have their good points and both have downsides. For speed and quality of casting, one-piece cut molds blow away clay-up molds. So I am very prejudiced in favor of them. Clay-up molds require much more labor to make and produce inferior castings because the parting line runs 100% around the object and it will never be as clean as a cut-mold parting line. Therefore the castings will require much more work to clean up. The next video I am releasing is titled “Why you’re afraid of silicone rubber cut molds”. It addresses the greatest fear people have which is messing up the parting line because they are cutting blind and can’t see what they are doing. I go over some ways to lessen the anxiety of the cuts. That said, you might want to do your crab legs as a clay-up mold. I did a lot of clay-up molds early in my career and that is why I appreciate how superior cut molds are. And it is useful to know how to do both.

[@s-n-sunlimited3604]

I have a mold making question and not sure where to email ot send the question??

[@GMCLabs]

So will this technique work with something like mold max 60? Its a high temp silicon that can be used for pewter casting. Working on something now and it would be a real pain to try and make a 2 part mold. Im not sure if mold max 60 is flexible enough to make a cut mold.

[@RobertTolone]

60 Shore A is mighty hard for a cut mold… People cast really complex figurines in pewter so there must be a softer rubber out there which can withstand the heat. I would check with your rubber supplier.

[@candlecocoon]

Thank you for the video. We sell lots of silicone molds that may need to be cut to be used. Would you mind if I shared your video to help folks figure out how to cut? It is a little different because our molds don't have the figurines inside. But I think it would still be helpful to show the straight cut on the inside and the jagged cut on the outside.

[@RobertTolone]

Feel free to share it. Thanks.

[@jenniferlynne10]

"SNERDLETTS" .....HA HA HA....TOO CUTE~!!

[@LaraArt1]

It's so funny that you offered this collaboration opportunity! I am an artist and I have just started making molds... leave it to me to sculpt 2 completely complex objects (an octopus and a sloth) . I searched and searched online for help with the octopus but i couldn't find anyone doing complex shapes with so many undercuts. I left the octopus and made my mold of the sloth... it sorta worked but I lost my original. Would you be able to help with the octopus? Its small...lol not house sized so hopefully you could figure him out :)

[@RobertTolone]

Hi Lara. Sure, email me pics and I’ll be happy to take a look at it. Thanks for watching! [e-mail]

[@donbrown8671]

Interested in the following project: a 8 inch tall coffee roaster with multiple curves, straight edges, and details. I've completed a sculpt in polymer clay and CX5. Currently has 4 pieces that can be molded/casted separately or glued together if that's the better approach.

[@RobertTolone]

What material do you plan to cast it with?

[@donbrown8671]

@@RobertTolone I'm flexible and ready to go with your recommendation(s). I believe the material you used in your car video is a good fit, but again, I'll defer to your judgment.

[@RobertTolone]

@@donbrown8671 You are actually going to roast coffee in it? How hot does it get?

[@donbrown8671]

@@RobertTolone Fortunately, it's a only model. It stands 7 inches tall and 2 inches wide. Im making it for my daughter who runs a coffee shop in downtown Boston. It'll be an ornament for the shelf. It's made primarily of polymer clay, but has some metal. the tricky part is the bean dispensing trays are about 1/16th of an inch. My daughter loves the prototype and ask me to make two others for the owner if the shop and the guy who operates the roaster. After countless hours making it, I'd really like to avoid making two more from scratch. Thanks for your consideration on this one.

[@wishcloudstudios]

Oh wow. What a great opportunity. But I am more of a hands on learner. I will get this mold making thing eventually. Do you need an apprentice? LOL

[@RobertTolone]

I Lots of students have worked in my studio over the years. In recent years I have worked by myself or in collaboration with other sculptors. I no longer have paid employees. Thanks for reaching out!

[@emiliebressler5982]

Hi! Can you help me figure out how to make resin mold for kitchen sink sponge? What product? different shapes?

[@RobertTolone]

I have no idea what material to use for making kitchen sponges. The easiest way to approach a project like this is to find people that are already making them.

[@leslieedwardshumez685]

I appreciate your presentations and professionalism! I'm a sculptor changing directions searching for a moldmaker and I'd be absolutely delighted to share a prototype with you for use in a video. Is there a way to contact you that isn't Dropbox?

[@RobertTolone]

Reach me at [e-mail]

[@leslieedwardshumez685]

@@RobertTolone Thank you. I'll be in touch.

[@ayezel6344]

I want to try to make a mold out of a creature's head, where the eyes are glass cabochons embedded inside the eye sockets. I want to be able to put the eyes in the mold and then pour resin and be able for them to be in the right place like the original clay sculpture. So far I will try with double-sided tape. Do you think this will work? A video with tips on how to resin pour with embedded objects would be cool. Thnx for your videos

[@RobertTolone]

The problem always is holding the embedded object tightly in the mold so that the resin does not dislodge it. I have never found a consistent, easy way to do this. I think the double-sided tape will create a gap between the rubber and the glass and allow resin to fill that gap. But you can do experiments to see if you can find a method that will work for your application. For me, I always prefer to add objects to a casting afterwards rather than trying to pot them in.

[@jazztlell]

Hi new subscriber here from 🇨🇦 anyway I have a emblem that im trying to remake. I'm restoring my 1977 ford f-150 that has a factory option canopy and theres 2 emblems on canopy that are weathered and kinda yukky I have some pictures of the product I could send you if you're interested in helping

[@jeffmanges874]

Have a project I would like to see how it’s done

[@RobertTolone]

Send pics to me at [e-mail]

[@davidedwards8480]

I have a few questions about mold release agents. In a production mold like this, how often do you apply a mold release? Just once? Before every new casting? Does the agent ever "build up" after many applications and degrade the mold details? Should you clean out the release agents before re-applying (and if so, how?) Finally, if you are making a mold of something that is glassy smooth, will applying a release agent dull the glassy effect? Thanks for your videos! They are a great help.

[@RobertTolone]

I try to avoid release agents. They do extend the life of the molds but they can also make it harder to paint the castings. The castings have to be thoroughly cleaned which adds a lot of work to the process. So I make enough mold cavities to complete the production run without release agents. if you do use release agents you only apply them as needed. Usually not between each casting. It’s a spray silicone so it doesn’t build up. but again, it is an extra step and therefore takes extra time. Smooth, shiny objects are problematic for resin casting. The silicone will perfectly duplicate the gloss and shine of a model but the resin will begin to degrade the surface of the rubber immediately so you will lose gloss with each successive casting. The release spray doesn’t preserve shine in my experience. I don’t have a lot of experience casting those kinds of objects because almost always I am going to paint my castings. But I do expect to buff and polish the castings that require a high shine. Keep in mind that resin castings change color over time. They get darker and more yellow pretty quick. If you want to make a permanent object that will keep its color and shine indefinitely you will need to paint and buff it out.

[@davidedwards8480]

@@RobertTolone Thanks for the reply. I am on the fence about using mold release. One more question I have is - on average - how many castings do you get out of a mold? I realize this can vary wildly depending on size and complexity. But as a rule of thumb, in a mold like the one featured in this video, roughly how many shots would you get before the mold degrades beyond use?

[@RobertTolone]

@@davidedwards8480 This is a complex subject because production casting is not just about mold life. It is also about how fast you can cycle the molds which dictates how long it will take to cast the edition. As a rule of thumb, I divide the total number of castings needed by 10. So for an edition of 200 I would make 20 mold cavities. I would want to cycle the molds twice per hour so I could cast 40 pieces per hour and finish the casting phase in five hours. But then there is filling speed. How many cavities I put into a single mold depends on how fast I can fill them. For instance, if a mold fills easily and rapidly I might make a gang of 10 or 12. But only if I can fill all the cavities before putting the mold into the pressure pot. But if the cavity fills slowly I would make a gang of five or seven. Otherwise I can’t get all the cavities filled before resin starts to gel. This is why it is very important to design the sprue and vent system to fill the cavities fast. Then there is mold expansion. The resin will heat the molds as it cures. This causes causes the inside of the mold to be much hotter than the outside and the difference in temperature distorts the mold. You begin to get a lot of flash in your castings. So you must equalize the temperature of the mold between casts. You can do this by cooling the mold or heating in the mold. Either way you must factor temperature control into your production process. See, this is a complex and multifaceted problem. Mold life is only one thing that contributes to the profitability (or lack thereof) of a job.

[@davidedwards8480]

@@RobertTolone It's that "lack thereof" I'm hoping to avoid! Thanks for all your feedback. You've been a big help.

[@Khanthetravelist]

I need help!

[@dessyred5785]

I cut a mold for easy release but when I pour the resin in it leaks out of the hole that I cut is there any way to fix this?

[@RobertTolone]

Silicone rubber will bond to itself so you can theoretically patch it. It will probably be very difficult to get a perfect repair

[@mikesfound]

It's very nice to watch your channel I've got several projects. Would love to speak about collaborations.

[@RobertTolone]

Contact me at [e-mail].

[@treblam1]

Any idea how many castings could be done on that one mold before the party is over for it?

[@RobertTolone]

It depends on many factors. What is the mold material, what brand is it? What is the casting material? How badly does it eat the mold? What is the surface of the model; smooth or rough? Fine detail wears out quicker. Are you using any mold release agent? How much heat is the casting generating? On and on. For most urethane castings in a silicone mold I usually can get 20 or so copies before I start to notice mold wear. Also, how old is the mold? They often go bad just sitting on the shelf.

[@RobertTolone]

For a mold on its last legs, use a barrier coat or mold release to coax more copies out of it. Always keep one of the first castings from a mold. That way you can always make more molds.

[@coulterjb22]

I just found your channel. I've been (poorly) casting metal for a couple of years and decided to get some real equipment. A vacuum table, an electric furnace, some wax for injection molding and some real investment (sorry Lowes and Home Depot). Do you do any/much injection wax molds for metal casting? (I'm just now going to search your library. I like your teaching style = Mastercraftiing!

[@RobertTolone]

The last time I did lost wax casting was making jewelry in high school! I have cast pewter alloy in high temp silicone molds but no actual foundry work.

[@coulterjb22]

@@RobertTolone Thanks for the response. Great channel. Could the silicone you use work for making multiple patterns from hot wax?

[@RobertTolone]

Yes, I pour melted wax regularly into my silicone molds.

[@coulterjb22]

@@RobertTolone If that silicone handles wax injection well, may I ask what silicone you are using? It looks like a Smooth-on product (I don't know many brands).

[@coulterjb22]

Oh geesh....I looked around your videos in the descriptions for the types of resins you used. You listed them right below my thread = fail. Thanks for your response. Great videeos.

[@crazycressy7986]

Hi again ,can I cast pewter using silicone moulds?

[@RobertTolone]

Yes, if you use a high-temperature silicone rubber.

[@crazycressy7986]

@@RobertTolone thank you Robert, I might as go the full 9 yards and do it right and then patina will be applied 👍

[@mbarlettaart]

I need some information on getting some molds made. How can I privately contact you?

[@RobertTolone]

Reach me at [e-mail].

[@leoisforevercool]

So would you say this is better than a two piece mold?

[@RobertTolone]

I would say a cut mold is almost always better than a two-part mold. Once in a while you have to use a two-part mold because the shape demands it. But almost never. At least in the world of character sculpting and casting.

[@leoisforevercool]

@@RobertTolone Perfect thank you so much!

[@saisiddu277]

Hi

[@wing6093]

can i assume the benefits of a cut mold are not gonna work if you are casting expanding foams?

[@RobertTolone]

The problem with casting expanding foam in silicone molds is holding the mold closed against the pressure of the expanding foam. That’s true of any silicone mold no matter how the parting lines were created. The rubber mold must be held tight inside a very strong case. I once did some Christmas ornaments using cut molds with foam and the biggest problem was getting the exact amount of foam into the mold for each unique shape. The process wasn’t very forgiving. Still I’m pretty sure that the vast majority of people casting expanding foam use two-part molds instead of cut molds.

[@jaspercoutu489]

Why would i still be getting an ugly seam line where i cut the silicone in my resin pours? I thought this was supposed to eliminate the seam line?

[@RobertTolone]

Are you cutting your parting lines jagged so that they interlock together?

[@jaspercoutu489]

@@RobertTolone i am! Still leaves a jagged seam line?

[@crazycressy7986]

I found a Roman hoard of artifacts ,and I want to make a mould of one of the faces in the hoard ,it's called the Roman licking dog hoard ,and its a bronze statue face fragment I want to cast ,its 2000 years old so it's going to be tricky, I am watching as many mould vids as I can

[@RobertTolone]

Cast bronze, is it porous or in good shape?

[@crazycressy7986]

@@RobertTolone it's the half face ,this was the first bit of the hoard to come out and made me realise it was Roman, the dig came out last, yes it's the star of the hoard but not for me

[@RobertTolone]

@@crazycressy7986 test your mold rubber against a small area of the bronze. Silicone rubbers are notorious for not curing against metals.

[@crazycressy7986]

@@RobertTolone great tip thank you did you get to see the link I sent ?

[@knmn2303]

I am new to mold making but have a few ideas I want to get done, please let me know what other information you may want.

[@RobertTolone]

Hi Jacqueline, email me at [e-mail] and tell me your ideas. Thanks!

[@crashoverride93637]

I have a hobby project, I want to cast a set of polyhedral dice i have a resin printer but everyone says platinum cure scilicone won't cure over uv resin and I dont have a pressure pot or vacuum chamber either. The dice are just going to be gifts to my Dungeons and dragons players so I'm not selling them

[@RobertTolone]

Send some pics to me a [e-mail].

[@crashoverride93637]

@@RobertTolone will do thank you very much for your considering my project I'll get those to you asap

[@levinebette15]

Have you ever ruined a mold by cutting?

[@RobertTolone]

Oh yes, in the beginning. I had no idea how to do it and there was no KZbin to help!

[@Mi.wagh786]

Can you tell us how you make money out of this how

[@RobertTolone]

The items in this video were sold to a retail store that sells them to the public.

[@TheZahnputz]

dont teach that molds with sculpted parting lines are generally bad, they just take longer to make. its the same as with being afraid of cutting your rubber - lack of technique. there is plenty of applications with various materials where the time saved by cutting has to be reimbursed somehow else

[@JOE_GOMEZ777]

Thats not true. It doesn't work for all molds

[@RobertTolone]

j g j g If what you mean is that cut molds don’t work for every situation, that’s correct. In my shop I mostly make toy-sized objects and have cast many hundreds of different shaped objects. And I have never clayed-up a parting line. Always cut molds. you learn to do what works best for the objects you are making.