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deke95

Super Strong Plaster of Paris

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I'm kind of new to TU, and to plaster casting, so don't know if this has been posted before. I bought some POP at the hobby store (Michaels) and tried making my first two molds (2-piece) which came out perfect the first time I tried. The plaster is called Strong Cast. The label touts it as the world's strongest Plaster of Paris. It says it has micro fibers in the plaster which makes it stronger. It is more expensive,...5 bucks or so for a two pound box, so might not be feasible for some who are making many molds, but for me it works great. It mixes easy, I used wooden ice cream sticks to mix. Stirred slowly, and poured SLOWLY, and had zero bubble problems. I used vaseline as a release agent and noticed that the cavity surfaces became very smooth, shiny and glaze-like hard after removing the injected hot plastic. The lure cavity appears so shiny and hard that it reminds me of fired porcellin. I have not sealed the lure cavity with anything yet. I don't know if this is normal to regular POP or not, as this is the only product that I've ever tried. I will probably seal the non-cavity area but am thinking I will leave the cavity area alone, as I am getting great detail with no noticeable wear. I carved a hard wax model, and set it in clay. I used a knock apart wooden mold box that I made out of scrap pine (four sides and bottom),.... clamped together with small pony clamps. After the pour hardened, I removed clamps and just tapped lightly on the box sides to knock apart and remove mold. Pouring the the other side went equally well,...makes a great 2-piece mold.

On one mold I wanted to add plaster to change the design a little bit. I scraped the shiny glaze down to clean plaster and mixed a small bit of new plaster and applied it to the scraped area with a modeling tool. After the added plaster hardened I sculpted in the new design and sanded it a little with 1000 grit paper.

The added plaster has withstood many castings, and you cannot see any telltale marks on the castings. Seems as good as advertised,..will keep using it until I find something better. I have lurked in here and received many tips,...hope this can help someone else a little bit.

Deke

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Randy from Hawg Pours told me about this stuff also. I think he uses a blend of regular and Strong cast.

Have you poured a bait in the unsealed cavity yet? I am curious if the bait will release and if the finish will be shiny or dull?

Good post!!!!!!

Jim

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I used vaseline as a release agent and noticed that the cavity surfaces became very smooth, shiny and glaze-like hard after removing the injected hot plastic. The lure cavity appears so shiny and hard that it reminds me of fired porcellin.

Deke - What I am reading is you made the mold and it wasn't hard, shiny and glaze-like until you put hot plastic into it. Was it some what dull before adding the hot plastic? Do you have any pictures?

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Maybe the vasilene became embedded in the surface and the heat of the plastic made it glaze over. You may have discovered a new way to seal plaster.

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Smallie

I had exactly the same thought about the heat reacting with the vaseline. I don't know if it was because of the Strong Cast plaster or not, because it's the only plaster I've ever poured plastic in. Before I poured the plastic, the surfaces of the mold were kind of soft and chalky like regular plaster looks and feels like. After a few castings, the cavity surfaces became hard and glaze like.

I know there is some kind of reaction happening between the heat and the vaseline, because I coated both surfaces of the 2-piece mold with vaseline and wherever the hot plastic squirted out in between, the same thing happened to those areas. I always thought vaseline was the release agent that you guys used for plaster molds. What release agent do you use?

Deke

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Reminds me of the hard tempering process of heating metal and then immersing metal in oil. Maybe there is some kind of similar action with the vaseline and heat that changes the hardness of the plaster surface.

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So when you pour a bait in the mold, does it stick to the mold surface now or do you have to add something to the mold surface every time you pour a bait.

Just curiuos as the Strong Cast I used still had to be sealed with elmers.

Jim

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I use Ultracal 30 instead of plaster and I don't have to use a release agent. When I used Water Putty, I didn't use a release agent either.

I seal with Devcon or Elmers, depending on how much shine I want on the baits. I have always been concerned that a release agent on "plaster" would soak into the surface and cause the sealer to lift off.

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Can you tell me where I can get some Strong Cast. I have tried the Michael's Craft Stores in Md and they don't stock it ..... it's not on there website and I can find very little info about it on the net (Google) ....... can find only 2 references to it but no source info...... Is there an address or phone number on the box?

Is there a phone number for the store where you bought it? I'd like to try some .........

Thanks in advance ......

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rhahn427,......

The only address on the package is: Webster Group, Redlands Ca. 92373. The Webster Group, Inc. - A Creative Arts & Crafts Company. Good luck on finding some!

Ghostbaits,.....I don't need to add any release agent or vaseline between casts. The baits do not come out shiny. Shiny isn't a factor with me yet, as I am only doing prototype casts and field test swimming action. When my plastic hits the water it's shiny to the fish though,...like spitting on a stone : ) ,...but if you need cosmetic shine for production casts you will probably need to seal. The hardness of the cavity area is what I like about Strong Cast,...the cavity is very hard and difficult to scratch,...but the non-cavity, untreated area is fairly easy to scratch.

Like I said before, I am new at this,...and these being my first two molds,.. I have more questions than answers about molds and pouring plastic baits. I don't know about the durability, or other characteristics for 100's or 1000's of casts as I have only done a few dozen protoype casts. Also, I am remelting some old plastic worms, so I don't have experience with new plastic.

Deke

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Just a follow up on this subject. After doing research it is recommended to use vegetable oil or baby oil. Now since I've never done this with the hot plastic I wonder how it is effected by the heat

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Try adding some yellow carpenter's glue to your POP after it's mixed to strengthen it.  It will hold details better.  1/2 cup+- in 4 cups of POP.

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