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You are here: TackleMaking Encyclopedia > How-To Guides > Plaster Molds
How to Make Plaster Molds for Soft Baits
This article was contributed by "Pole Pimp", a member of the TackleMaking community.
How To Guide: Plaster Molds for Soft Plastic Lures

When making soft plastic fishing lures, the first thing you need to do is make a good mold. I have been using Plaster of Paris. It works okay for the hobbyist, but is not a good solution for large volume or production manufacturing. (I will be doing research on better alternatives for an upcoming article).

I use aluminum pie pans for my molds because they are relatively cheap and the plaster doesn't stick to them at all. After the mold dries, you'll want to coat the plaster with a sealant like Mod Podge. This makes the mold harder and fills in the tiny pores in the plaster to prevent imperfections in your lure. If you don't apply the sealant, the plaster will tear apart and break and the worm will stick to it. The sealant can be applied using a kidís paintbrush.

There are many different ways to go about designing your mold. You can modify a bait already on the market for your own personal use, or create your own design from clay or wood. I personally like using clay to make a design I like. I then bake it in the oven to harden it. When it is done cooling, I coat it with Mod Podge. After the Mod Podge has dried and I'm ready to make my mold, I take the clay lure and rub a very small amount of Vaseline on it to keep it from sticking to the plaster. If you don't, you'll wish you had!

Making the Lure Design - Step by Step
1. Make the design out of clay
2. Harden the design - Follow baking instructions on box of clay (some brands don't need to be baked)
3. Coat the hard clay lure design with a sealant such as Mod Podge and let dry
4. Coat the lure with very thin layer of Vaseline.

Making a Basic 1 Part Mold - Step by Step
1. Fill a small aluminum pie pan with Plaster of Paris.
2. Press the Vaseline-coated clay lure into the plaster and allow the plaster to dry around it. Make sure you leave the top of the clay lure exposed. You should not allow any plaster to cover the exposed portion of the lure.
3. When the plaster is hard, remove the clay lure.
4. Seal the mold cavity with Mod Podge.

Using a Basic 1 Part Mold - Step by Step
1. Pour the liquid plastic into the mold cavity
2. Allow it to cool
3. Remove the cooled plastic lure
4. Place the lure in a bowl of cold water
5. Remove from water and lay straight on a paper towel to dry
6. Trim off any overflow plastic

Now that you can make your own simple molds, I'll tell you how to make more detailed double molds. The double mold allows you to make a full casting of the lure design, similar to injection molded lures.

Making an Advanced 2 Part Mold - Step by Step
1. Fill a small aluminum pie pan HALF WAY up with Plaster of Paris.
2. Press the Vaseline-coated clay lure HALF WAY into the plaster, leaving the top half exposed. When you set the bait in the mold you'll want to make sure one side of the lure is close to the edge of the pan (about a half an inch of less is good).
3. Add two or three Vaseline-coated bolts to the plaster so they stick up and out of the mold. These will serve as guides for the second mold layer so they match up exactly during the pouring phase.
4. Allow the plaster to harden around the lure.
5. Coat the surface of the plaster with a thin layer of Vaseline.
6. Now pour on the top layer of Plaster so the lure is completely covered. Pour enough to fill the pan to the top.
7. Allow the top layer to dry.
8. After the top layer dries, CAREFULLY turn the pan upside down and allow the plaster mold to slide out.
CAREFULLY take the two mold layers apart. To do this, I use a putty knife that I tap in between the two layers...very softly working my way around the mold. The key to this part (and the whole process for that matter) is to take your time. If you don't, the mold will break.
10. Now you will need to make a pouring hole. I use a scraper I bought at a craft store. It resembles a dentistís scraper. Start scraping away the pouring hole from the inside out (from the edge of the mold cavity toward the edge of the mold). Do this to both layers of the mold so the pouring hole lines up when the two layers are connected. Keep scraping until you have created a hole large enough to pour plastic through.
11. Now you will need to make the venting hole to allow air to escape as the plastic is poured in. To do this, scrape a thin hole from the mold cavity to the edge of the mold in another part of the lure. When you are done, you should have two holes running from the edge of the mold into the mold cavity - a venting hole and a pouring hole.

12. Coat the the insides of the molds (the mold cavity and the holes) with sealant and let it dry.
I also coat around the outside of the hole in case I overfill it, or miss the hole. This will prevent the overflow plastic from mixing with the plaster (so you can reuse it later)

Using a 2 Part Mold - Step by Step
1. Connect the two sections of your mold using the bolts to line it up
2. Slowly pour the hot liquid plastic into the mold through the pouring hole.
3. Fill the mold until the plastic is just about to overflow through the pouring hole
4. Allow the lure to cool in the mold
5. Pull the two sections of the mold apart.
6. Remove the cooled plastic lure
7. Place the lure in a bowl of cold water
8. Remove from water and lay straight on a paper towel to dry
9. Trim off any overflow plastic

*Always wear safety goggles and follow instructions provided by the manufacturer or supplier of the tools and components you are using. TackleMaking is not responsible for any damage (personal, property, or otherwise) that results from reading, following, or referencing this article and/or performing the actions described within it.

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