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Molds & Accessories for Producing Quality Pewter Miniatures
Easily and Profitably.

INSTRUCTIONS  ADVANCED INSTRUCTIONS
IMPORTANT NOTE

IT'S EASY - QUICK - SAFE - AND RELATIVELY INEXPENSIVE

GREAT FOR REPRODUCING MINIATURES, SPECIAL PARTS, MEDALLIONS, BUCKLES, LOST WAX FORMS FOR JEWELRY MAKING AND MANY OTHER USEFUL PRODUCTS USING YOUR OWN MODELS.

EASY: No mixing of materials or the construction of a pouring box. Everyone can expect good results from symmetrical models when the simple instructions are followed.

QUICK: Durable, reusable molds can be made and used within one hour. No more waiting two to three days to finish a mold.

SAFE: Non-Toxic. No harmful materials or mess.

COST: Compared with RTV materials (room temperature vulcanization) the cost of making your own molds can be reduced by 40% or more.

THAT'S IT! SIMPLE, FAST ECONOMICAL, FUN AND IT CAN BE VERY PROFITABLE.

Please read the following instructions completely before attempting to make your first mold. Take your time and familiarize yourself with all of the procedures. After investing your money you will want to obtain satisfactory results which can only be accomplished by following each simple step.

Working with our uncured silicone rubber is similar to working with modeling clay. ft is non-toxic and any mistakes made before you heat the material can be filled in and you can start over. Also, some mistakes or imperfections can even be corrected after the material has been vulcanized. You will find the silicone material is very forgiving and easy to work with.

SELECTION OF MODEL: Your selection of the model to be used is important. The model may be made of metal, wood, plaster, glass, shell or high temperature plastic (polycarbonates, nylon or Teflon). The model must be able to withstand a temperature of 375 Deg. F. The model must also be able to withstand the high internal pressure exerted on it during the vulcanization process, and the forces required of inserting it and closing the mold. The model must be of a size that the VULC-A-MOLD can accommodate, allow for a pouring gate, have 1/4" clearance on all sides, and maintain a minimum of 1 /8" wall thickness between the model cavity and the outside of each of the mold halves.

The model you select should basically be symmetrical which will allow the silicone rubber to flow around the model evenly and the parting line will be located at or near the center line. Molds to be made from non-symmetrical models (called "Build-Up Molds") are the most difficult type of mold to prepare because of the un-equal parting line required. We strongly suggest that models with an irregular parting line be avoided until you have a good deal of experience using the VULC-A-MOLD. Please refer to the "Special Instructions for Preparing Build-Up Molds".

The model should be free of any paint as It may react unfavorably with the rubber during vulcanization. You may use a paint remover if this is necessary. Afterward, clean the model with vinegar and dry thoroughly. Do not use soap, soft woods (balsa), fragile pieces, low temperature plastics, or a figure with undercuts as your model. (An undercut is where there is a surface below or underneath another such as an overhang.) Using a model with the above features would create a mold that would likely tear when attempting to remove it or the cast parts. Heavy undercut areas should be avoided wherever possible or filled in before vulcanizing with a clay that will harden such as Das Pronto or an epoxy material. This will extend the molds casting life and reduce problems in removing the castings. Later, when you become familiar with the vulcanization process, you can attempt to make molds using figures with undercuts, by removing certain parts, casting them off to a side assembling them afterwards.

Be aware that the mold will reproduce any scratches, mars, or imperfections on the model. In addition there will be a slight shrinkage so the castings produce~ will be about 4% smaller than the original.

If you are unsure of the models ability to withstand the temperature place it in the oven to be used and heat it at 375deg.F. for 45 minutes. It is better to fail at this point rather than lose the model, expensive rubber and your time and effort.

GETTING STARTED: Spray both inside cavities of the VULC-A-MOLD with the Parting Spray (always allow the spray to dry 5- 10 seconds before handling or dusting). In addition dust the cavities with the white dusting powder. You will find that using a dusting brush is helpful. Blow off any excess.

Spray and dust all sides of each rubber slab, then firmly press the preformed silicone slabs into the cavities.

Completely spray the model to be used. More than one model can be placed into the mold if the models can be positioned satisfactorily (review first paragraph under "Selection of Model"). Remember a pouring gate must be directed to each model cavity.

Place the model on one rubber slab and press slightly to make an impression into the rubber Using a pen knife cut and remove enough rubber to press the model in halfway or to its parting line. It is critical that you do not remove too much rubber as the pressure from the expansion during vulcanization is vital to obtaining good detail in the mold. If the mold closes completely on the first closing without some rubber being displaced you have removed to much and some of the scrap cut out will have to be replaced.

Spray and insert the preformed sprue (pouring gate) if it is an acceptable size for the model being used. If this size is not practical you will have to cut the appropriate pouring gate after vulcanization.

Insert the mold handles and tighten securely. Now close the mold using steady pressure. You will note that the model is displacing excess rubber. When you can no longer close the mold with moderate pressure open it and remove the model. Do not hammer or use clamping force to close the mold. Don't expect to displace all the excess rubber on the first closing.

Spray your knife blade with the Parting Spray then dust it. Blow off the excess. Now lay the blade over each side of one of the mold halves and with a slight sawing motion move the blade across the top of the mold cavity removing the excess rubber. Do this over each slab. Save the scraps as they can be used later. It is important that the knife blade is well sprayed, dusted and drawn smoothly across the surface as you do not want to scar the metal surfaces of the mold tool. As a safety precaution always move the knife blade away from you.

After removing the excess rubber, spray the rubber surfaces again. Replace the model and repeat step 6. Continue this process until the mold tool can be completely closed. At this point open the mold tool and remove the model and rubber slabs. Remove any rubber that has been pressed in the undercut grooves of the mold tool allowing space for rubber expansion during vulcanization. Next trim off any rubber squeezed onto the side of the slabs squaring them up.

Spray and dust the mold cavities again. This must be done each time to prevent the rubber from sticking. Spray the rubber and model and reposition them in the cavities.

Next insert the cap nut locators. Press them halfway into the rubber about 1 /4-3/8" away from the model and at least 1/4" in from the edge of the mold . Spray a final light coating on the rubber, model and locators. Dust lightly and blow off any excess. The locators will insure that the mold halves line up properly later.

Clean the metal mold faces of rubber3 spray and dust and before the final closing (See illustration 6). This is very important so that little or no rubber will ooze out during vulcanization. You may use a finger to rub clean the metal face or a lint free cloth moistened with Acetone or Trichlorethylene.

Close the mold and tighten the four Allen cap screws securely using the Allen wrench. It is important the mold be completely closed before proceeding. Check this by holding the Vulc-A- Mold up to a light. If any light is seen between the mold halves you must repeat the closing process above to remove the excess rubber or particles on the mold faces. The mold must be closed all the way to achieve satisfactory results. The time spent in preparation now will be well rewarded with the amazing results that are possible.

Preheat your oven to 400 deg. F. Remove the mold handles. When the proper temperature is reached place the mold in the oven. Do not ever vulcanize in a Micro Wave oven. During vulcanization the rubber will expand and a small amount may ooze from the Vulc-A-Mold. If the above instructions have been followed this will not affect the results. It is the heat and the pressure created by the expansion of the rubber that will cure the rubber and give it its excellent detail. Heat the mold tool for 60 minutes then remove it. It will be hot so wear gloves when removing it. Allow the mold to cool about one hour before opening it

Remove the four locking screws.. Replace the mold handles and attempt to open the mold f you are unable to open the mold with moderate pressure on the handles place a screw driver blade between the handle bosses arid twist to assist in opening. Do not insert the screw driver blade between the closed faces of the mold tool as it could damage the face surface and prevent successful future use of the tool.

After the Vulc-A-Mold has been opened pry the cured rubber out of the cavity using a screw driver blade if necessary. Use a sharp knife or safety razor blade to trim off the flashing around the outside of the mold. Rubber that was talced and sprayed properly should separate easily, if it does not use a small screw driver and pry around the parting line until it opens and can be pulled apart by hand. Remove the model. if a small section of the model is encapsulated by rubber, you will still be able to remove the model and later castings. Initially, you must carefully slit the rubber directly above the encapsulated area with your sharp pen knife or safety razor blade and then flex the mold. The model can be removed, and the castings poured later should be removed in the same fashion, The rubber will close over itself, but you must take care not to tear it further when removing the castings. Now place one drop of oil on each hinge so the tool will continue to pivot freely during future use.

If the mold has not cured completely (rubber is still soft and gummy) you can put it back into the Vulc-A-Mold with the model and heat it again for 45 minutes at 400 dig. F. This is also a method of repairing a damaged mold using the scraps of clean uncured rubber saved. Remember if you attempt to vulcanize rubber together both surfaces must be free of Parting Spray3 dust and dirt or there is a good chance the rubber will separate and not become a permanent part of the mold after vulcanizing. Be certain to keep these surfaces clean or clean them with Acetone or Trichlorethylene. Spray and dust each side before closing the Vulc-A-Mold. Before the final closing of the mold tool you must clean the metal faces of spray and dust or leaking will occur during vulcanizing. Insert the Allen screws and tighten securely.

IT IS IMPORTANT THAT YOU USE ONLY THE RUBBER MADE SPECIFICALLY FOR THE VULC-A-MOLD. IT HAS BEEN FORMULATED TO BE NON-TOXIC AND TO CURE AT 400 deg. F  IN 60 MINUTES.

GATING THE MOLD: Cut the pouring gates if necessary. The rubber cuts easily so use caution not to damage the mold. It is important to use sharp tools in making the cuts so change blades frequently for best results. The best gates or vents are those which are smooth and not having many small slices There is no exact science when it comes to gating and venting as it is more of a learned technique but the following are some helpful tips:

Round and tapered Gates are preferred as the center is an equal distance to the sides and this allows for a good flow of the hot metal. It is best to first draw your gate shape and size onto the rubber with a ball point pen and then make your cuts. The opening of the pouring gate should be about 1 /2-5/8" in diameter (the opening on each mold half should measure about 1 /4-5/ 1 6") The gate should taper off to about 1 /4" as it enters into the mold cavity. The cut should be made at a 45 deg. angle. The cut material can be removed by your finger or a tweezers. With a piece of sand paper you can round out the gate path.

The gate should enter the cavity at an obscure place such as the base of a figure In that way it will not create the problem of distorting the figure or part when the sprue is broken off and filed down.

POURING YOUR CASTING: See the instruction sheet enclosed for pouring your silicone rubber mold. In addition to pouring metal you may cast with casting wax, fast setting plastics and certain resins.

After you have become completely familiar with the process of making molds having a straight parting line without severe undercuts you can advance to the more difficult mold making projects. Read through the following instructions until you understand the methods presented before attempting to make an advanced mold.

Types of Advanced Molds:

FLAT TOP MOLDS- are made when the model is sunk completely in one half of the mold and the parting line is produced on the model's top surface. This type of mold can only be made with a model having either a flat top or bottom surface) with absolutely no undercuts on the sides.

BUILD-UP MOLDS- are made when using non-uniform (not symmetrical) shape models. These are the most difficult types of molds to make because of the unequal parting line required. The unvulcanized rubber must be cut out and molded to shape by hand prior to vulcanization and the mold maker must develop and appreciation for the parting line and undercuts which through experience and several mistakes, he should develop quite quickly.

MULTI SECTION MOLDS- (3 or 4 part molds) are used on models having severe undercuts (i.e. horse legs when not scissored) which can not be handled in a standard 2 part mold. This type of mold usually includes a molded in 3rd or 4th rubber section which pulls out from the mold.

Build-up Molds probably are the most difficult to prepare. We will attempt to describe the best techniques to follow, but experience and some mistakes will be the best teacher.

1. Determine where the parting line of your model is. For assistance take a felt tip pen and draw the parting line on the model.

2 Do not spray the top surface of the rubber at this time. Only after the mold is properly prepared can it be sprayed or dusted. The reason for not spraying the model at this point will become clearer as you read and work on.

3. Because the rubber is pliable in the unvulcanized state, you can press the model into the rubber. In most cases you will be able to press the models down to the desired parting line location. The rubber has a memory therefore it is necessary to push the model slightly deeper into the rubber. On models with uneven and deeper sections) you will have to cut away or scoop out the rubber first. Only remove that amount of rubber that will allow you to reach the parting line locations. The rubber removed should be kept clean and put aside as it will be used later in preparing the remainder of the mold.

4. Always smooth out the cut away cavity areas with a clean smooth instrument. (see supply list at end of instructions)

5. On models which have heavy undercut sections that stick up much higher than the mold surface after the model has been pushed into the rubber) you must build-up rubber in that area. Place clean (unsprayed) rubber under or adjacent to these higher sections until you reach the parting line location.

Note:you must work with clean unvulcanized rubber during build-up and it is recommended that you first clean off the mold surface with Trichlorethylene or any other quick drying commercial solvent (such as our DioSol) to provide for a good rubber bond. If the mold surface or buildup rubber has dirt) dusting powder or parting spray on it, there is a good chance the build-up area will separate and not become a permanent part of the mold after vulcanizing.

6. Smooth off the built-up area with a clean smooth instrument.

7. After you have cut away and built-up the rubber where required remove the model carefully and then completely spray all the cavities, built-up areas, and the entire surface. Dust the surfaces also.

8. Spray the model again and carefully place it back into the prepared cavity.

9. Place in the cap nut locators.

10. In those sections that have been cut away for the deep model sections, stuff in the clean unvulcanized rubber that was previously removed from these areas. it is important that you only stuff in approximately the same amount of rubber that was removed, and no more. After stuffing, cut off any excess rubber that might be sticking above the mold surface. Put your finger in a clean cloth and dip it into your solvent and completely clean and wipe the top surface of the stuffed rubber with the solvent. This will assure that the rubber will properly bond to the opposite mold half.

11. insert the sprue former.

12. Spray the opposite metal cavity. Place the second rubber slab over the slab that is in its mold cavity. DO NOT spray or dust the surface of this rubber slab. Enough parting spray is on the opposite half to provide separation. If parting spray is sprayed by mistake the stuffed sections of the mold will not bond to the top half of the mold.

13. By hand, press down on this top slab. Those sections that are much heavier or higher in the cavity below will cause the top slab to bulge on its top surface. These areas must be trimmed away from the slab. This is done quite easily by closely following the contour and thickness of the bulge with a sharp pen knife blade. Remove the cut away rubber strip from the slab. Repeat this step until the slab is lying practically level.

14. Close the Vulcanizer following the instructions from the first instruction sheet you received. Lock with the 4 cap screws.

15. Remove the handles and vulcanize according to the instructions.

If it is imperative that the parting line is produced exactly right, which is common on some irregular shaped models) or if you have encapsulated any portion of the model, all is not lost.

If a small section of the model is encapsulated by the rubber you still will be able to remove the model and castings. Initially, you must carefully slit the rubber directly above the encapsulated area with your sharp pen knife and then flex the mold half. The model can be removed and the castings will be removed in the same fashion. The rubber will close over itself but you must take care not to tear it further when removing the castings.

If you are intending to work on a production basis and the encapsulation section does not lend itself to be removed as described, or an exact parting line is critical do the following:

After vulcanizing, the model will remain in that half of the mold in which it was sunk to deep or having encapsulated sections. The other half of the mold can be discarded. Carefully remove the model. Using your pen knife evenly cut or shave away the rubber to the required parting line location around the entire cavity. It may be helpful to place back the model every once in a while for guidance. After the cavities have all been cleaned up, place the mold half and Vulc-A-Mold in the oven for a few minutes to warm up the rubber as it has shrunk about 2% at room temperature. Then place the model back into its cavity. Take one new slab of unvulcanized rubber and spray its surface. Place it over the slab In the mold cavity and trim away any bulges until it lies level. Spray the metal cavity, close the Vulcanizer and lock it up. Vulcanize at 400 for 1 Hour.

Multi Section Molds (3-4 parts)

Prepare to make this type of mold as described in the Vulc-A-Mold instructions under Getting Started. If the model being used is a horse where the legs are not scissored and an insert section would be needed to part the mold after pouring, a special mold section is then required.

This special section is first removed from the unvulcanized rubber. This is done by evenly cutting out the required size and thickness from the rubber slab. Shape the pull-out section by hand to fit between the horse legs. Use as much material for the insert as was removed. It should fit fairly closely but complete accuracy is not necessary as it will conform exactly after vulcanization. Both sides of the cutout section are to be sprayed and dusted with talc. The pull-out rubber section is carefully put back into the mold in its proper position. The mold is prepared for vulcanizing and the pull-out section is vulcanized with the mold.

After vulcanization the mold will have a completely removable section for the heavy undercut configuration of the component.

Flat top mold preparation: Spray and dust the mold frame cavities. Lay unvulcanized rubber into the Vulc-A-Mold cavities. Spray and talc the rubber. Layout the model. Place in the mold cap locators and vulcanize per instructions.

IMPORTANT NOTE

We found that this latest batch of uncured silicone rubber vulcanizes best in the Vulc-A-Mold tool at 400 degrees F for one hour.

This is a change from the directions give in the instructions and applies only to the current batch of rubber being shipped.

Also, it is very important that the uncured rubber be well sprayed and dusted prior to closing the tool.