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sealer for plaster molds ?

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Hi guys. I have finally made a few decent plaster molds for hand-pouring soft plastic. I have also discovered the need to seal plaster molds before pouring plastic. I have tried mod-podge with "OK" results, but i'd like to get away from brush-strokes. I've heard of Devcon 2-ton epoxy, but it sounds like that is also brushed-on. What is the latest-and-greatest ?

Has anyone tried the spray-can glaze for plaster at Wal-Mart ? Thanks for any help !

Alan

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I use the Clear Satin Polyurethane spray from Walmart and have no problems. The only downside is it takes a couple days of drying time before you can pour. If you try to pour too soon, the plastic will pull the poly from the mold, causing bubbles or ripples in the bait. Once that happens, the mold is ruined. :|

Chris

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Hi Guys. I recently tried Walmart's "Triple Thick Gloss Glaze" for sealing a plaster mold. It is not the answer that I was looking for. Several sprayed-on coats were needed to seal a plaster mold, and it didn't dry as hard as I would like. I'm pretty sure that it would peel, similar to mod podge. I also tried the Devcon thing and I'm very happy with the results. I just have to learn to be careful about loss of detail.

Thanks for all the help and advice !

Alan G

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Now the really DUMB question is.........

Why dont we coat the lure in the fiberglass resin, let it start to set up, then finish off with the plaster???????

Get the finish that lasts and didnt need to use a whole quart at a shot.

Darn now thats actualy a fairly good idea if the two will combine.

Oh the resin is found at wal-mart, or even the auto body supply, Best store so car was farm and fleet, 7.25 for 32 oz. Wal mart is 9.98 per quart too. (fiberglass resin, polyester resin is the same thing)

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New at this, but have made 4 or 5 molds over the past month, using suggestions from this board. Sealing the plaster molds is a problem. I've used mod podge and then sprayed with engine enamel. Works, but got some separation from the plaster. Still not happy with the sealing method. It's probably very important to make sure the plaster is very hard and cured completely(think I'll use the defrost cycle on the Micro to speed curing). I think the separation problem may be from lack of patience. I'll be watching for any updates, as I molded a new 2 piece last night that I would like to turn out right.:?

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Mercury. your idea will not work as you will never get the fiberglass resin off the lure !!! As far as the plaster goes IT MUST BE DRY! I bake mine for about 6 hours or so on top of a old pancake grill. Works great to keep stuff warm. For 1 piece molds just glue the plastic bait down to a plastic or pyrex pan then pour.

For 2 piece molds here is how I go about making mine. First you get plain ol plaster of Paris. I got mine at Wally world (Wal-mart) LOL Ok get a soft plastic container big enough to hold your master bait and about 2" high. ( You can use Lego's made in a box for this and put them on a sheet of glass with wax paper or Vaseline on it.) Next get a pattern. This can be a soft bait that you want to copy of or a piece of wood that you have carved to look like what you want your finished bait to look like. (Anything other then soft plastic baits has to be coated with Vaseline) Take your plastic container and rub Vaseline all over the inside. pour about 1" of plaster in the bottom take your master or masters for multiple cavity mold and stick it down into the plaster a little more then half way . I found out it works better to have all the molds patterns the same direction. Makes it much easier to pour. Ok , I use a flat small board to push it down so it stays flat. Then I push 2 marbles covered in Vaseline down in half way or a little less and jiggle the container a little to try to get the plaster to flatten out. Make sure the patterns don't come up out of the mold. Push the plaster out of the container after about an hour, take your masters out, & take your marbles out.

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Take a full sheet of sandpaper put it on a flat table or surface and sand the bait side of the mold to get it flat this should only be a 1/16" or less to get off the high spots. Then you let this part dry for about a day. Coat the mold with Vaseline again and put it back into the container.

Put the pattern and marbles coated in Vaseline back into the mold, coat the sides of the container with Vaseline again. Now pour about 1" of plaster on top of this. and let dry for an hour. Push the 2 molded pieces out of the container and carefully pry apart at the seam line with a big knife. Take the pattern out and smooth up any ruff edges with your finger. Let this dry for about a day.

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OK the piece you poured last is the top of the mold. Turn it bait side up and drill a sprew hole?? (Not sure how to spell it) Drill Pour hole about 3/8" up through what would be the head of the lure then turn it over and counter sink that some with a large drill about 3/4"(see pix). Leave about a 1/4" of the 3/8 drilled part on the bottom of the hole

Next drill a hole about an 1/16 of in. for the air to escape on the other end.

Paint on a couple of thin coats of Fiberglass resin. Let dry and your done. This type mold works great for round type baits with no flat side, like senkos or swim type baits. Just block up the mold on the side you pour into about an inch, that way the plastic runs down and you get no air boubbles. This does not work well to make thin tailed baits as the plastic dries before it fills the mold all the way. You can also make stand up molds that you pour into the end this same way. They work well also, OK happy pourin.

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Mercury. your idea will not work as you will never get the fiberglass resin off the lure !!! .

Well Fish n fool, many of us do use the fiberglass resin as a molding material.

I have several and others make them too.

The resin does come off the lure. Might want to read up on several discussions previously.

http://tackleunderground.com/board/viewtopic.php?t=521&highlight=resin

http://tackleunderground.com/board/viewtopic.php?t=1015

Woodsac also had given more info about building the resin molds in a few other posts too.

Dont need to add epoxy or other sealer, lasts for a good long time. Just make sure that the master is nice and smooth so you dont get other dull baits.

Now if your looking to cast from a original master, You need to use Red's silicon mold tutorial. cast a few lures, then use them in the poly resin.

From what I have seen of plaster, It will set up in water, adhears to other materials. etc, But it is brittle.

I was just looking at a way to keep the detail that you get from resin molds, but make it cheeper if possible.

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What ever finish you use it is important to completely dry the plaster mold before applying it. I use the sound the mold makes when tapped with the back of your fingernail as a guide to how dry it is. A perfectly dry mold will have a ceramic 'clink' or 'ring' sound, an under-cured mold sounds dull. This can take up to a week to obtain this level of dryness. I have a rack behind my wood stove that I use to dry the molds, and it takes several days at about 150 deg. F.

If you are impatient and coat the mold too soon, then pour 300+ deg. plastic into the cavity, steam will form inside the plaster, seperating the finish from you mold.

By using a thin epoxy, like a bar top finish (in several coats) you can get a finish which actually penetrates the surface of the mold. I can't imagine it ever peeling off.

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Mecury , I have also made molds from resin. Although I don't think it works as well as plaster ones. But you have to use a release agent like vasilene or you will never get a hard bait out ot the resin. It was my understanding that you were going to paint the figerglass resin right over the pattern and then pour plaster over it. It would not work that way and if you coat the lure in vasilene the resin would not stick to it to coat it evenly.

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Resin has a 'shrink factor' making it harder to build two part molds.

If you are breaking the top half of your mold, I would suggest two things; Make sure to use a good release agent. You can use a layer of foil, or saran wrap around the edges of the joint to help get it to seperate.

Mix your plaster VERY thick, then allow it to cure overnight before seperating the two halves.

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Mecury , I have also made molds from resin. Although I don't think it works as well as plaster ones. But you have to use a release agent like vasilene or you will never get a hard bait out ot the resin. It was my understanding that you were going to paint the figerglass resin right over the pattern and then pour plaster over it. It would not work that way and if you coat the lure in vasilene the resin would not stick to it to coat it evenly.

Ohh, I get it, I wasnt thinking of hard lures. I was thinkinig like this,

get the lure and either pour a small ammount of resin on the lure or use a paint brush and try to controll it a bit more.

If you used worm oil on the lure the "worm" doesnt stick.

I wasnt looking at trying to use it as a sealer by itself, After it starts to set up then yes you add plaster to it. (strong cast actualy) 3x stronger than plaster.

Now the only thing is it is a bit too cold in the garage. Being 8 degrees yesterday not including the wind chill I couldnt get the chill off the garage with my torpedo heater.

30 min later and I still see my breath..... = too cold for me.

Like Al's momma doesnt like it when I do things inside the house...

If that didnt work then I was going to make a plaster mold with a trough in it. then add the resin and add the lure.

If plaster doesnt work then I will try several other mediums.

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