Foam Baits Mold Material
9 replies to this topic
Posted 19 November 2009 - 09:14 PM
If I cast my bait model with Durham's Water Putty,and coat the cavities with D2T ..... will the foam stick to the mold?
NOTE:I have made a few rtv silicone for pouring foam baits .....
But when the foam expands,it tends to push out on the mold and the baits become inconsistent ..... I want a more rigid mold for my foamies,and thought that I would get a opinion from the experts.
Thanks for any info. that you guys can shed on this.
Posted 19 November 2009 - 10:57 PM
I tried Plaster of Paris for foam, it was a total disaster.
I am sure that you will have to stick with the RTV and find a way to make it work. I think correct venting will be the solution, allowing the excess foam to escape and avoiding the pressure built up. Maybe backing the mold with plywood might help, by spreading the clamping pressure and preventing the mold from 'bulging'.
Tighter controls ofer the mix, by weighing with a gram scale, reducing the amount each time. It will not be practical to try and nail the mix to exact, as temperature has an effect on the expansion, as does the mixing process. You have to mix/stir the same every time.
I moved away from foam too soon, without giving it a proper chance. I hope you do better, as it is an excellent material for lures.
ps. sorry, misread your post. I suspect it would stick, that was my problem with Plaster of Paris. Hopefully someone can suggest a super dooper release agent that would solve the problem for you.
Edited by Vodkaman, 19 November 2009 - 10:59 PM.
Posted 19 November 2009 - 11:24 PM
If you have experience with RTV, I'd stick with it. Look around for a higher durometer (harder) variety.
Urethane foam LOVES to glue your molds together. It's tough enough with RTV (I'd still recommend a release).
Could you cast in putty or plaster?, sure with enough mold release, longevity of the mold would suffer IMO.
Bondo/poly resin might be slightly better....... again, stressing a release agent over the entire surface. A small bit of flashing and she's sealed shut.
edit: adding for release agents...
I use "Mann's Ease Release 800" for silicone.
For porous molds like plaster, id hate to venture a guess, maybe paste wax??
Paste wax should suffice for poly resin, I've never personally tried it.
Posted 20 November 2009 - 03:49 AM
Can you specify the lenght of the lures?
For small , under 3" lures I also use RTV and foam from smooth-on(15lb 4X - expand) and never had a problem. I make the mold in a plastic pipe(there is a tutorial about this on TU) after that I do an evacuation hole on one side, then I place the mold on two large duck tapes but leaving the hole free for the foam to evacuate
Also as a tip, I use an X-Ray plastic for pouring the foam in the mold. I bend it and press it with my fingers, like that you will obtain a channel on the plastic. Mix the foam on it, plie the plastic, separe the mold opening, put the plied X-ray in it and let the foam go down. This way the foam won't get on the RTV opening, if it gets there gently wipe it with soft paper(napking)because it will expand and will open the mold, your lure will become fat.
Note: this is 1 piece molding
Posted 20 November 2009 - 04:00 AM
don't worry, you have plenty of time to do all of that before the foam expands. Also use the napkin to wipe the foam of the X-Ray plastic cause you can use it several times. The down side of this method is that you'll have to drill holes and use twisted eyes and also drill a hole or two for the weight
I'm working on a mold with pre-cut channel for thru wire and holes for the weight, I have a blue RTV and a pink one. The blue is 1:1 mix ratio and it's better then the pink one that has a 10:1 mix ration. This stuff is great, on 1" lures I have an 0.03" lip slot and it gets perfectly on each foam lure so I think it won't be a problem on the thru wire channel
Sorry for the pic quality, it's made with my mobile phone
Edited by pikeman, 20 November 2009 - 04:03 AM.
Posted 20 November 2009 - 04:08 AM
Maybe I'll do a tutorial for this the pics are more concludent than the words
Posted 20 November 2009 - 10:45 AM
Hey pikeman really appreciate the info (sorry for hijacking the post)! Your pics have encouraged me to try a one-piece mold. You think something similar to your mold could be done with a 3-piece swimbait?
Posted 20 November 2009 - 12:11 PM
A-Mac, I wouldn't encourage this method for a 3-piece swimbait unless you split it in three different molds, remember that you can't place the hardware in the mold so you'll have to do it after you demold the pieces. Working with foam it's different than urethane and microballoons, you don't have time to place enough foam for a 3-piece lure before it starts to expand. If you figure a way for this or if you have any thoughts share them and will discuss pro and cons maybe there is a way to do it
P.S. here is the tutorial for the mold
Edited by pikeman, 20 November 2009 - 12:16 PM.
Posted 20 November 2009 - 09:39 PM
Thanks for the replies.....
I really do need the through wire in the baits that I'm planning to make at this point and,I think that I will take REDG8R's advise to look for a stiffer RTV.
I really like the one piece mold with the pipe idea (I had forgotten about seeing that tutorial before),I will be using it for other molds in the future.
Thanks again guys.
Posted 20 November 2009 - 10:03 PM
I was hoping to do something similar to what Lary Dalbherg did in his lure making episode and roll pure resin around in the lure to form a shell. I've never used foam before so I would probably just fill the void up with resin and microballoons. I remember someone mentioning this before to potentially reduce the number of pin holes in the surface. I figure that this could also strengthen the lure that much more (since fillers weaken the resin). I actually don't install any hardware except the line tie until later in the process too. It is still a few weeks off before I can try anything like this, but I'm sure it will take time to figure out how to map out my channels properly. Thanks for posting that tutorial! I don't think I looked at that one since I first joined!