dtrs5kprs Posted April 10, 2003 Report Share Posted April 10, 2003 Just finished making some "mother" or "master" molds for some RTV molds I wanted to reproduce. Used Smooth-On's 2 part pourable resin, with excellent results. Basically, I formed an aluminum foil bowl or container around my original RTV molds, leaving just a little space around the edges of the molds. Then I just mixed up the resin and poured it in, starting by filling the cavities and then working out towards the edges. Took about 15 minutes to get fully cured and cooled, then just peeled the foil and popped out the RTV mold. What is left behind is a resin "box" with resin pours of the cavities molded into the bottom. I used a dremel to smooth up the edges of the box a bit. Before pouring the RTV I sprayed a couple of coats of Smooth On's mold release in the resin "mother" mold. Once the RTV is cured, you just need to peel back a corner or side, and gently separate the RTV from the sides of the "mother", and peel it out. BAMMO...you have just reproduced your original mold. This is a MUCH better way of reproducing molds (esp compared to pinning/gluing and pouring over multiple baits. Have made about 6 so far using the "mother" molds and there is NO variation mold to mold. Eliminates all the fumbling around with foil/tupperware types of mold boxes. Also cuts back on RTV waste because it is much easier to estimate the volume of the mold container (could also trim excess RTV from the original mold before the casting the "mother" to further decrease waste: such as trimming around a large curl tail). Have made them for 4" (zoom type) finesse worms, big flipping grubs, and 3" grubs so far...think there might be some issues on ribbed/zipper type baits (related to mold release). In sort of a time crunch this week...packing to leave for Table Rock Sunday night...but will try to get some pics of this process/these items up ASAP. It works so well, I thought I needed to get the info out ASAP. It could really make buying commercial molds cost-effective. I have made LOTS and LOTS of molds, from all materials (except aluminum I guess) and this is by far the fastest and easiest method I have ever used for replicating your original. Quote Link to comment Share on other sites More sharing options...
alsworms Posted April 10, 2003 Report Share Posted April 10, 2003 Bring on the Pictures. That sounds REALLY cool Quote Link to comment Share on other sites More sharing options...
The Drop Shot Store Posted April 11, 2003 Report Share Posted April 11, 2003 I second that. That makes so much sense I cant believe we havent been doing it that way already. Outstanding job Quote Link to comment Share on other sites More sharing options...
kidlizard Posted May 13, 2003 Report Share Posted May 13, 2003 Sounds like you have the RTV thing down. I have been trying to put off using it because of the expense, but the plaster thing just isnt working to great for me. PLease post pics of the process and all materials used. I would like to give this a try. "Exact" duplicates in plaster are a real pain. Looking forward to seeing the results. Thanks John Quote Link to comment Share on other sites More sharing options...
redg8r Posted May 13, 2003 Report Share Posted May 13, 2003 Great Idea Dave, As soon as I pick up another gallon of SC300, I'm gonna try it. The master itself might be a lil, (meaning little expensive, but the fact of having a master mold, that is practically indestructable, to re-fab your production molds, far outweight the price of the resin. I thought about using bondo resin instead, but the heat reaction makes for too much shrinkage from the original. Thanks, Quote Link to comment Share on other sites More sharing options...
kidlizard Posted May 13, 2003 Report Share Posted May 13, 2003 Red, What is SC300? I assume thats the resin to make the master with. Where can I get it. I have experimented with bondo resin like you said, and it gets really hot and the shrinkage is very noticable. With the SC300, do you just mix it up and pour it over a RTV mold, then pop it out and duplicate? That sounds really easy. What about making copies from a plaster mold? You think it would work. Thanks in advance guys.....John Quote Link to comment Share on other sites More sharing options...
redg8r Posted May 13, 2003 Report Share Posted May 13, 2003 Red' date=' What is SC300? [/quote'] Yup, its SmoothCast, available from Smoothon.com its a 2 (equal) part resin, cures in 10 minutes to a hard, white plastic. Its what I use to make my poppers with. With the SC300, do you just mix it up and pour it over a RTV mold, then pop it out and duplicate? That sounds really easy. What about making copies from a plaster mold? You think it would work. It seems so, I havnt tried it yet, but what i'd do is build up a wall around one half of your mold (or use the original mold container) & pour the resin & let cure........Then do the other half (if your doing 2 part molds) Only issue I see with plaster is, if you have an undercut in the plaster, you will likely break the plaster trying to get the resin & plaster mold apart. but its well suited for reproducing rubber & silicone, Im sure. If you currently seal your plaster molds, I dont see why you couldnt use plaster as the "mother" mold material also...... worth a shot.... Remember, what your doing is casting a "negative mold" (bait included), so you can in turn cast your production molds from the negative (mother) mold. Maybe Dave will stop back in & relate us some more info. Quote Link to comment Share on other sites More sharing options...
kidlizard Posted May 14, 2003 Report Share Posted May 14, 2003 G8R, Thanks for the info!! One more question.....where is the best and cheapest place to buy RTV silicone to give this a try. I have a few lurecraft molds, and I would like to experiment with those first. Then I will also try out the plaster and let everyone know how that turns out. Thanks again...John Quote Link to comment Share on other sites More sharing options...
redg8r Posted May 14, 2003 Report Share Posted May 14, 2003 G8R' date='Thanks for the info!! One more question.....where is the best and cheapest place to buy RTV silicone to give this a try.[/quote'] I havnt really done a price comparison, but Smoothon offers an affordable RTV: (Omoo line of RTV) http://www.smooth-on.com/silicones.asp $22.00 for lil over a liter I'm sure it cheaper somewhere, I coulnt get Alumilite to send me a pricelist, maybe check polytec, but I think thier RTV shrinks. I've been using straight silicone, but its not pourable. If anyone else finds a deal, id love to hear about it. Quote Link to comment Share on other sites More sharing options...
kidlizard Posted May 14, 2003 Report Share Posted May 14, 2003 Thanks G8R! Any idea on how many 2 cavity molds I would get out of a liter? I just found your tutorial on 100% silicone. (awesome) I assume this could work with a "mother" mold also? I think I will give it a try. I just want to make hand pour molds, not ready for the 2 part stuff yet. With silicone can I use a regular soft plastic as the master, or will I have to make one out of resin? Any suggestions with the one piece molds from silicone? Also can I add color to the silicone for visibility reasons. I think I read somewhere from you before that water based paint can be used as the catalyst? Thanks John Quote Link to comment Share on other sites More sharing options...
redg8r Posted May 14, 2003 Report Share Posted May 14, 2003 Any idea on how many 2 cavity molds I would get out of a liter? Depends on your baits' date=' couldnt tell ya for sure...... think of a Pepsi one liter bottle, thats about right for the rtv quote mentioned above. With [100%] silicone can I use a regular soft plastic as the master, or will I have to make one out of resin? Dont see why not.... just lay your bait out, make a frame around it & brush a thin layer on the bait, after it sets up you could just goop the rest of the silicone in to build up the mold. Also can I add color to the silicone for visibility reasons. I think I read somewhere from you before that water based paint can be used as the catalyst? Yeah Ive added acrylic paint instead of water, but the first few pours pulled some of the paint out of the mold, so i switched to H2O, it works the same to me. A good thought would be to pour a thin layer of RTV to ensure exact detail, then backup the thin rtv layer with the 100% silicone. you could make the RTV go alot farther that way. wet silicone will bond to dry silicone, so you can go in small layers if you like. What I like about the 100% silicone is that I can cure it in an hour & score it at the hardware store. air bubbles has been my only issue with it. Quote Link to comment Share on other sites More sharing options...
Pop Posted July 10, 2003 Report Share Posted July 10, 2003 I have only poured a few plastic baits in the past but would like to do more of it sometime. However at one point I was interested in buying some mold making silicone from Lure Craft and sent them an email inquiring about cost and how many molds could be made from a certain quantity. After doing some calculating, it seemed considerably cheaper to just purchase the molds from lure craft instead of making them myself. I sent an email to Lurecraft explaining the results of my calculations and they never replied to me. I never persued it any further, but; would be interested in knowing if it is actually cheaper to make your own molds or not? Right now I don't think it is cheaper to make your own. Doesn't make sense but that's why I am asking. Thanks Quote Link to comment Share on other sites More sharing options...
The Drop Shot Store Posted July 10, 2003 Report Share Posted July 10, 2003 If I remember correctly a liter of rtv is roughly two pounds and change. As an example, a 5 cavity production mold for 3.5" drop shot baits takes 4 oz. of rtv, so you get 4 molds per pound if I dont goof on the silicone weight. Pops - It can be cheaper to make your own molds if you buy the rtv in large quantities. If you have designed your own bait and are selling them, then this is the way to go. For personal use I would imagine it would be hard to beat L-C stock mold prices. I'll pass on my process for making production molds in case anyone has actually read this far. I make a master out of clay. When I'm satisfied, I'll cook it and shoot it with urethane. I then make a single cavity mold using rtv poured over the above master. I'll pour a few worms out of this mold to make sure things look the way I want them to and that it isnt too difficult to pour efficiently. I'll pour up 8 to 10 resin castings. Pick out the best 5 and glue them down to a piece of Lexan. Shoot the whole thing with urethane and let dry for a few days. You now have a mold master than can be used over and over to make molds. Quote Link to comment Share on other sites More sharing options...
Mercury Posted July 10, 2003 Report Share Posted July 10, 2003 Nice Tip Bruce! Im looking at mass production of swim baits, This can make things go really fast! Thanks. Quote Link to comment Share on other sites More sharing options...
Pop Posted July 12, 2003 Report Share Posted July 12, 2003 Bruce, how do you make the master from clay? Does it require hand molding, carving, in other words do you need an artistic talent to do this. My four thumbs always get in the way. Pop Quote Link to comment Share on other sites More sharing options...
The Drop Shot Store Posted July 12, 2003 Report Share Posted July 12, 2003 I hand carve them. It took quite a bit of practice because while I have a creative mind, I dont have Michael Angelo's hands. But let me encourage you to try it yourself. It can be a very satisfying process. Dont look at the whole project all at once, just try and rough out the body shape first then take a break for a few hours or even a few days. Your mind will refresh itself and may have even come up with a better shape. Then start working on the details. It may surprise you how well it comes out. And if it doesn't, wad it up and start over. On my best couple of baits, it took me roughly 3 to 4 weeks to complete the clay masters. I would love to show pictures of them but I dont want them copied. They aren't on the web site and I only sell them locally. That may change though. Take care. Quote Link to comment Share on other sites More sharing options...
redg8r Posted July 12, 2003 Report Share Posted July 12, 2003 I gotta agree with bruce, take your time & realise you wont make a perfect master in one sitting. just get your basic shape & then harden the clay, then you can work on top of the basic shape. If you mess up just remove the fresh clay & start again. Once I get an area that looks good to me, I stop & harden the clay before I proceed any farther. Dont get discouraged if the final result dont work like you thjought it would, the swimbait I recently finished sure looks good, but After testing some initial pours I found I need to lengthen the tail & make some other adjustments, so its back to square one for me. Once you do get a good working bait from your hard work, youll be pleased & it will have been worth the effort for sure. Quote Link to comment Share on other sites More sharing options...
Pop Posted July 13, 2003 Report Share Posted July 13, 2003 Thanks! I never thought of doing it that way. By using the clay you don't need to go back to square one every time you make a mistake, just back to the last hardening. Is there any special clay that is better than others, and is this another item you can get from Walmart or a craft store? Also is there any special way of hardening or just stick it in the oven until hard? Thanks for all your help. Pop Quote Link to comment Share on other sites More sharing options...
redg8r Posted July 13, 2003 Report Share Posted July 13, 2003 I dont know which clay bruce is usin but I'm usin a polymer plastic clay called super sculpey (aka sculpey, fimo etc.) its a crafting/sculpting clay. it cures in the oven at @ 275deg. for 15 min. Weve had a few good discussions on it in here, do a search on "clay" & you should get the topics of interest. Good luck pop Quote Link to comment Share on other sites More sharing options...
The Drop Shot Store Posted July 13, 2003 Report Share Posted July 13, 2003 I'm using the sculpey. Tried most others and I always come back to it. Play with it some, get a feel for how you work with it and what you can and cant do. Dont worry about slight surface irregularities as you can sand them out after you cook it. I have a little sheet of Lexan than I do mine on while I'm watching TV. It's easy to get the master off of when it comes time to bake it. When you buy the clay, pick up a simple clay carving tool set. Should be about 4 bucks and will give you most of what you need for carving different shapes and such. When it comes to adding texture or scales, look around the house and see if there are things lying around that will give the desired effect. Usually they are right in front of you. Most of all, have fun doing it, and allow yourself some patience with your initial work. After a week of practice, you will surprise yourself. Take care. Quote Link to comment Share on other sites More sharing options...
Fish_N_Fool Posted March 3, 2007 Report Share Posted March 3, 2007 I have been doing this for a long time in a differant way. I can't believe you guys haven't been doing this all along too. I made a master out of a durhams mold by just placing my durhams mold in a metal pan just big enough to hold it with about 1" of space all around. Then I heated up all my old junk plastic I had laying around and poured over the mold. After it cooled I pulled the plastic out of the pan and removed the durhams mold leaving a perfect copy of it in plastic. Now all I have to do to get a new durhams mold is pour the plastic master full of durhams and a perfect match to the original pops out. This would make exact repilacs of your pop molds too. try it, works great! Quote Link to comment Share on other sites More sharing options...
MicroSalm Posted March 5, 2007 Report Share Posted March 5, 2007 Guys while surfing the internet I came accross what I found to be the best instructional videos for RTV molds. Check it out! http://www.tapplastics.com/info/video.php Quote Link to comment Share on other sites More sharing options...
