My Rtv Bubbled

[patrick reif]

I poured a 2 peice rtv mold of a 7" sucker grub. The side I poured first came out just as I wanted with the exception of a few bubbles in the tail. The second pour, I used PAM cooking spray to act as a release agent, and the RTV Has the look of the interier of a Nerf football. There are thousands of super tiny bubbles and tiny air pockets throughout.

What happened? I've heard PAM was an acceptable release agent

BTW, I'm still going to pour this grub because I don't think the fish give a crap one way or the other...I just don't want it to happen again. We're talking a $50 investment afterall.

[Piscivorous Pike]

I poured a 2 peice rtv mold of a 7" sucker grub. The side I poured first came out just as I wanted with the exception of a few bubbles in the tail. The second pour, I used PAM cooking spray to act as a release agent, and the RTV Has the look of the interier of a Nerf football. There are thousands of super tiny bubbles and tiny air pockets throughout.

What happened? I've heard PAM was an acceptable release agent

BTW, I'm still going to pour this grub because I don't think the fish give a crap one way or the other...I just don't want it to happen again. We're talking a $50 investment afterall.

I feel for you, by the time I finished one mold, a copy of the Javallon, I had $250 into it. I could have bought a supply of the originals for that! A gallon or 27T rtv is $100 (85 + freight!)

I have used aerosol non stick stuff and noticed that some of them would fizz like soda pop. I suspect that the oil became saturated with the disolved propellant gas, just like soda pop, it then fizzed. What saved the day was to allow it to air out and the fizzing stopped. Sometime, depending on the substance, a blast from a hair dryer or a fanned flame from a small torch will pop bubbles. I pop bubbles in POP, DWP, plastisol and RTV that way. The generic PAM popped when just aired out.

Edited May 9, 2010 by Piscivorous Pike

[gone2long]

Sounds like a chemical reaction? Are you using the PAM to release the RTV from itself or the master from the RTV?

[smallmouthaholic]

Although there are ways around your problem,that's precisely why i stopped using RTV after making close to 100 custom molds and went to custom CNC molds. You only buy them once and they're precision. There are different types of RTV silicones rated for different temperatures.

Do not coat your bait w/ anything.

Call Jon Flint @ advanced materials -800-327-8787 for your 10 pd. kits of RTV silicone.

[Husky]

I poured a 2 peice rtv mold of a 7" sucker grub. The side I poured first came out just as I wanted with the exception of a few bubbles in the tail. The second pour, I used PAM cooking spray to act as a release agent, and the RTV Has the look of the interier of a Nerf football. There are thousands of super tiny bubbles and tiny air pockets throughout.

What happened? I've heard PAM was an acceptable release agent

BTW, I'm still going to pour this grub because I don't think the fish give a crap one way or the other...I just don't want it to happen again. We're talking a $50 investment afterall.

OK, listen up.... Put a dab of silicone caulk on your finger tip and ply it into the mold cavity. Create a glaze. It will lay smooth and fill in all the holes and imperfections, guaranteed.

I've used Pam with none of the effects you mentioned. I can't help you there.

FWIW, I've reduced the cost of RTV mold malking by using just enough RTV to barely covering the model, allowing it to cure and then fill the remainder of the mold box with the Silicone caulk water mix.

Edited May 9, 2010 by Husky

[stratmanv]

Patrick,

I have never tried RTV for the simple reason of cost, instead I have spent a couple of years trying to master the use of POP for 2 part molds. I figured if I screwed it up up all I would be out was a few cents per try. There is a wealth of information on this board about the subject which is where I got my start, and have since played with different ideas until I got to the point to where I can reproduce just about anything with POP. This pic is to give you an idea of the quality of detail you can acheive and the gloss after being poured. Now this is a copy of an aluminum mold reproduced with POP, but the same result can be had from copying an actual bait. I have many times wondered about trying RTV for a 2 part mold, and always have a hard time getting past the thought that is is simply too plyable and would require the mold to be made very thick, which as you know is expensive because of the cost of materials needed. One thing I have learned about making 2 part POP molds is this..the first half of the mold almost always comes out bubble-free. The next step requires some method of preventing the second half from sticking to the first. I started by trying vasoline, a thin coat over the entire surface of the first half that I poured. Although that does work I always seemed to get some form of bubbles in the top half. The thin coat of vasoline on the mold face after the mold dries, also makes it difficult for the 50/50 mix of elmers/water to soak in to all the micro holes in the POP which left dull spots on the poured bait. The key to getting around this is twofold..only brush a thin layer of vasoline around the edge of the first halp, maybe a 1/4 in. The other thing I found is that if you wait until the first half is completely dry, you will surely get a ton of bubbles as all those micro holes in the dry POP will release air bubbles when the watery second layer is poured. I now pour my second half as soon as the first layer has hardened, although it is still no where near fully cured.

Like I said, it takes some trial and error, but at least your error doesn't cost an arm and a leg. I know I have strayed from your primary question, but I hope I gave you some ideas about an alternative that could help you save a few bucks.

[gone2long]

Patrick,

I have never tried RTV for the simple reason of cost, instead I have spent a couple of years trying to master the use of POP for 2 part molds. I figured if I screwed it up up all I would be out was a few cents per try. There is a wealth of information on this board about the subject which is where I got my start, and have since played with different ideas until I got to the point to where I can reproduce just about anything with POP. This pic is to give you an idea of the quality of detail you can acheive and the gloss after being poured. Now this is a copy of an aluminum mold reproduced with POP, but the same result can be had from copying an actual bait. I have many times wondered about trying RTV for a 2 part mold, and always have a hard time getting past the thought that is is simply too plyable and would require the mold to be made very thick, which as you know is expensive because of the cost of materials needed. One thing I have learned about making 2 part POP molds is this..the first half of the mold almost always comes out bubble-free. The next step requires some method of preventing the second half from sticking to the first. I started by trying vasoline, a thin coat over the entire surface of the first half that I poured. Although that does work I always seemed to get some form of bubbles in the top half. The thin coat of vasoline on the mold face after the mold dries, also makes it difficult for the 50/50 mix of elmers/water to soak in to all the micro holes in the POP which left dull spots on the poured bait. The key to getting around this is twofold..only brush a thin layer of vasoline around the edge of the first halp, maybe a 1/4 in. The other thing I found is that if you wait until the first half is completely dry, you will surely get a ton of bubbles as all those micro holes in the dry POP will release air bubbles when the watery second layer is poured. I now pour my second half as soon as the first layer has hardened, although it is still no where near fully cured.

Like I said, it takes some trial and error, but at least your error doesn't cost an arm and a leg. I know I have strayed from your primary question, but I hope I gave you some ideas about an alternative that could help you save a few bucks.

Dude nice work, man that looks like white CNC aluminum

[Vodkaman]

Awesome mold, congrats.

I recently experimented with making a vacuum box, using a shop vac. The results for PoP were amazing. Pretty much zero bubbles.

This would not work for RTV, as the viscosity would not allow the bubbles to escape. But for the low viscosity of PoP, it really worked and is now part of my standard practice.

Dave

[Piscivorous Pike]

Awesome mold, congrats.

I recently experimented with making a vacuum box, using a shop vac. The results for PoP were amazing. Pretty much zero bubbles.

This would not work for RTV, as the viscosity would not allow the bubbles to escape. But for the low viscosity of PoP, it really worked and is now part of my standard practice.

Dave

Dave,

please post a thread on this new box, you and I have been experimenting with vacuum systems, this is new. At least send me a pm about it.

thanks in advance from all of us on TU who tinker!

[Vodkaman]

Will do Pikey.

Dave

[stratmanv]

Thanks guys. Dave, would love to hear more about that myself..

[patrick reif]

I poured the plastic today. This is my first attempt at 2 peice molds and sculpy clay, so be kind.

The tail needs somemore trim work, but I'm fairly certain the fish don't care. The bubbles are hardly noticable up close and can't be seen in the pictures.

The color was 1/2 teaspoon of pearl white powder, 21 drops of pumpkin, 10 drops of greenpumpkin, 5 drops of purple in 1 cup of plastisol(all Del).

I smeared black flake on the top part of the mold and gold flake on the sides before pouring.

The blade holder is just some 80# test steel leader material that I twisted like a cork screw and laid in the mold. I cut a slot in the rtv to hold it in the center of the mold. This is alot easier than trying pour around the jig. The blade is a size 2 wide willow on a ballbearing swivel

The jig is a 6/0 VMC with a 3/16oz shakeyhead. I had to modify my mold to allow it to fit.

This is my first completely homemade bait.

Expensive, but fun

edited to add; I have to pour the tail first or the plastic won't reach the tip, thus the need to trim

Edited May 11, 2010 by patrick reif

[t-billy]

Patrick,

I have never tried RTV for the simple reason of cost, instead I have spent a couple of years trying to master the use of POP for 2 part molds. I figured if I screwed it up up all I would be out was a few cents per try. There is a wealth of information on this board about the subject which is where I got my start, and have since played with different ideas until I got to the point to where I can reproduce just about anything with POP. This pic is to give you an idea of the quality of detail you can acheive and the gloss after being poured. Now this is a copy of an aluminum mold reproduced with POP, but the same result can be had from copying an actual bait. I have many times wondered about trying RTV for a 2 part mold, and always have a hard time getting past the thought that is is simply too plyable and would require the mold to be made very thick, which as you know is expensive because of the cost of materials needed. One thing I have learned about making 2 part POP molds is this..the first half of the mold almost always comes out bubble-free. The next step requires some method of preventing the second half from sticking to the first. I started by trying vasoline, a thin coat over the entire surface of the first half that I poured. Although that does work I always seemed to get some form of bubbles in the top half. The thin coat of vasoline on the mold face after the mold dries, also makes it difficult for the 50/50 mix of elmers/water to soak in to all the micro holes in the POP which left dull spots on the poured bait. The key to getting around this is twofold..only brush a thin layer of vasoline around the edge of the first halp, maybe a 1/4 in. The other thing I found is that if you wait until the first half is completely dry, you will surely get a ton of bubbles as all those micro holes in the dry POP will release air bubbles when the watery second layer is poured. I now pour my second half as soon as the first layer has hardened, although it is still no where near fully cured.

Like I said, it takes some trial and error, but at least your error doesn't cost an arm and a leg. I know I have strayed from your primary question, but I hope I gave you some ideas about an alternative that could help you save a few bucks.

Rtv works great for two part molds. There's no need to make them overly thick. I've been pouring them just thick enough so I only cover the bait by maybe 1/8". I cut pieces of plywood to match the mold and sandwich the mold between them when I clamp it together. I use vaseline as a release agent. I set the masters in pop.Then pour the 1st half using the bombs away method. The next day I flip the rtv over in the box pull the masters out and smear a very thin coat of vaseline over the whole face including the cavities. This will help hold the masters down in the cavities during the 2nd pour and ensure that if any rtv gets under the masters it won't stick to the 1st half and ruin it. Make sure you smear a bead of vasiline all the way around the perimeter. Rtv is very viscous and will run down behind the 1st half if you don't. Pour the 2nd half and the next day you have a 2 part mold. I cut my venting channels with an exacto knife. I'm no expert but,this method has been working well for me. Get good with the pop 1st. If you do that,rtv is easy.

[onlyonmonday]

Stratman..

I am GREEN..

I ask this from the darkness about the POP mold in post 6..

What are the lines coming from the cavity for ?? Release air or ______ ??

Are all molds set with the channels ??

Edited January 31, 2011 by onlyonmonday

[stratmanv]

Stratman..

I am GREEN..

I ask this from the darkness about the POP mold in post 6..

What are the lines coming from the cavity for ?? Release air or ______ ??

Are all molds set with the channels ??

Yessir they are vents for air release, helps avoid air pockets in your baits.

This is a copy of an aluminum mold so the venting was done in the original cutting of the aluminum.

Most, if not all, cnc aluminum molds have them.