While the basic color ofForton is white, it can be pigmented with water-base pigments in order to achieve a variety of effects, including a very convincing "marble." Metal powders may be added to the Forton producing a superior metallic finish which may be patinated in the same manner as any cold-cast metal.
Cabosil or aerosil (glass powders) may be used to thicken the Forton mix (see tips further down on this page). Or one may use accelerator (see more detailed explanation further down this page.)
When measuring, mixing or otherwise handling metal powders, dry resin, powdered hardener, cabosil or any other powders associated with the Forton mix, a high-quality (NIOSH-approved) dust mask must be worn; as all of those materials represent some degree of toxicity if inhaled. Once these powders have been dispersed into the liquid polymer through mixing, the dust mask may be removed.
A gram scale is required to weigh-out the various components that comprise the Forton casting system.
Biaxial Fiberglass is a superior woven fiberglass that conforms much more closely to the contours of a mold than does conventional woven fiberglass which tends to bunch into folds, trapping air-bubbles. The biaxial fiberglass will stretch-out much more effectively, and will be about 30% stronger than an equivalent weight of ordinary woven fiberglass. We at Pink House Studios use biaxial fiberglass in all our fiberglass-reinforced Forton castings.
Forton Starter Kit
Because the Standard Forton Starter Kit has been planned specifically for casting projects involving metal powders, there is an insufficient quantity of FGR-95, Dry Resin and Dry Hardener (based on the amount of liquid polymer included) to make-up the entire kit as plain Forton (without metal powders.) If you refer to the mix ratio chart, you will see that the proportion of FGR-95, Dry Resin and Hardener to the liquid polymer is less for mixes that use metal powders. For a long time, this standard unit has therefore been less than ideal for people with small projects that wanted to cast in plain white Forton. Pink House Studios has heard your requests, and we now offer TWO DIFFERENT Forton Starter Kits to address this discrepancy:
STANDARD FORTON STARTER KIT (for use with metal powders) including:
Approx. 1 one-gallon bucket VF-812 (7 -lbs.)
ten-lbs. FGR 95
1-lb. pkg. Dry Resin
one 22-gram pkg. Hardener
2-lbs. Fiberglass Chopped Strands (3/4-inch)
GENEROUS FORTON STARTER KIT (for casting in plain white Forton) including:
Approx. 1 one-gallon bucket VF-812 (7-lbs./
1 .4-lbs Dry Resin
31-grams of Hardener
2-lbs. Fiberglass Chopped Strands (3/4-inch)
Forton Sculptor Kit..............................................................$145.00
Includes: five-gallon bucket VF-812 (40-lbs.total weight)
eight (8) 1-lb. packages Dry Resin (8-lbs. total weight)
eight (8) 22-gram packages Hardener (176-grams total weight)
Forton 55-gallon drum (includes the powders).......................$1200.00
Please note : FGR-95 is not included in the Sculptor Kit or with 55-gallon drum, as it is readily available in most locations. For the location of a distributor of FGR-95 near you, phone US Gypsum at (800) 621-9532.
Fiberglass is also not included in the Scuptor Kit or with the 55-gallon drum, and may be purchased separately as follows:
10-lb. barrel Fiberglass Chopped Strand (3/4").$35.00
12-oz. weight Biaxial Woven Fiberglass.........$14.00 per sq.yd.
1 bag, 3.75-lbs. of 500 RL Copper Powder.............$40.88
1 bag, 3.75-lbs. of B-178 Brass Powder................$61.88
1 bag, 3.75-lbs. of B-409 Bronze Powder...............$60.00
1 bag, 3.75-lbs. of C-306 Nickel-Silver Powder........$67.50
Please refer to our print catalog for full technical information regarding the
FORTON casting system.
Re: Cabosil use with FORTON
Cabosil (colloidal silica) is a fine silica powder generally used as a thickening agent for FORTON or for resins.
So that your casting will pick-up all of the fine details of your mold, cabosil should be mixed into the FORTON for the initial one or two brush-coats, before reinforcing the cast with fiberglass and Forton.
Always wear a dust-mask when mixing cabosil, because it is
an extremely fine, light powder that literally floats in the air.
Add cabosil slowly, a little at a time; and mix very slowly so
it doesn't all fly up into the air. Use a mixer attached to a
drill for this purpose.
Once the cabosil has been dispersed into the Forton mix, you can raise the speed on your drill to a higher level and blend until the consistency is perfectly smooth. You want to achieve a viscosity (thickness) that is a little thicker than molasses, or a loose mayonnaise. If it is too thick, brushing will be difficult, and it will be hard to get good surface contact without trapping air-bubbles. Too liquid a mix will cause the Forton to sag or run down the sides of the mold and pool in the bottom. Remember to add the cabosil only in small amounts, a little at a time. Otherwise you risk making your Forton too thick. It doesn't take much cabosil to reach the ideal consistency
Cabosil will not affect the strength or working-time of Forton. You will want to bush back-and-forth across the surface of your mold to make sure that you are getting good surface contact, and then immediately build-it-up with the same mix to about one-eighth-of-an-inch thickness. If you think that you will need to do a lot of sanding because your mold is rough, etc. (e.g. plaster bandage texture),you may want to apply a second coat to an additional thickness of about one-sixteenth-of-an-inch. Otherwise, one-eighth-of-an-inch will be plenty in any Algiform or Ply-O-Life mold.
Let that cabosil thickened layer cure or set for about one
hour or more, and then mix another batch of Forton (without
cabosil), and soak your precut rectangle or squares of fiberglass
in the Forton mix. Lay those over the partially cured Forton-and-cabosil
coat(s). It is a good idea to brush a little Forton to each area
of the cast, just as you are about to apply the soaked fiberglass
there. This aids in the bonding. If you were to brush the Forton
everywhere right away, it would set in some areas before you had
a chance to lay-up the fiberglass there.
Don't get too far ahead of yourself!
Your fiberglass should be well-soaked; and you need to lay in two layers of fiberglass. The most efficient way to do this, is to overlap everywhere by half, as you go along applying each piece. Wear thin Nitril or latex gloves because the Forton dries quickly in thin layers over skin, and it is difficult to remove after you have been working for half an hour or more.
Re: Excluding air in solid FORTON castings
When casting in solid Forton (for hand molds etc.), you will want to exclude as much air as possible from your mix so that your finished casting will not have visible air bubbles. Pressure casting, or using a de-airing or vacuum system will eliminate this problem. However, if you do not have these options available to you, you will want to observe the following procedure:
After mixing-up your Forton, allow it to rest for about 30-minutes. This will allow the air-bubbles to rise in the mixture and break on the surface. You must check it every ten minutes or so and remove any "skin" that may form on the surface; otherwise, this skin will prevent more bubbles from rising to the surface and breaking. Use a spatula to lift-off the skin, and throw it away. After thirty minutes have passed, pour the Forton mixture gently and slowly into your mold. Pour it so that the material runs down the sides of the mold. This way, you will not trap a lot of air-bubbles in a "waterfall effect", which can occur when material is poured straight down into a container (your mold).
At about 40-45 minutes, your Forton will suddenly start to gel, so your pour must be completed before 40-minutes after your initial mix time
Thickening Forton with Accelerator:
If you are doing a hollow casting in Forton, and want to brush a face-coat into your mold without it constantly running down and pooling in the bottom, you will want to thicken your Forton mix. At Pink House Studios, we don't use cabosil (or aerosil), because these silica powders are so light that they float in the air, posing a genuine hazard when they are inhaled. Also, if cabosil has been added to your Forton, no matter how well it was mixed, when you sand the finished surface, you will find that tiny pin-holes are exposed. Our solution for thickening Forton is to add some accelerator to the Forton instead of the cabosil or aerosil. The accelerator for Forton is a mix, by weight, of one-part aluminum sulphate to ten-parts warm water (so that it dissolves more quickly.) Shake this solution until it is entirely dissolved. Aluminum sulphate is readily available at any gardening supply place. It is very inexpensive and is used as a soil conditioner for flowers etc. It comes in a whitish crystalline form. Usually, when we mix-up a big batch of Forton for a casting project, it will be the maximum amount of material that our triple beam balance scale can handle. This mix would break down to the following components:
. A plastic bucket, coated inside with a thin film of petroleum jelly and "zeroed-out" on the scale, into which we put 1,150 grams of liquid polymer (VF-812).
. A second plastic bucket, also "zeroed-out, holding 2,300 grams of FGR-95.
. Next, 230-grams of dry powdered resin is added to the FGR-95 bucket.
. Then, 11.5-grams of dry hardener is added to the FGR-95 and the dry powdered resin; and the three powders are mixed well with a scoop.
. Finally, all of the powders are added to the 1,150 grams of liquid polymer (VF-812). Mix as you add the powders; it is essential to use a drill with a mixer attached.
We can then pour-off smaller amounts of this mix. We usually pour-off about two cups (total: 16-ozs.), or the equivalent of a large paper coffee cup. To this, we add about two tablespoons of the liquid accelerator, and we mix that very well; either by hand, using a spatula; or with a small mixer attached to a drill. This is then poured into the mold and brushed over the entire surface, going up the sides of the mold, and brushing back and forth across the textured areas, etc.
Once the accelerator has been added, you will have about five-ten minutes of working time. Then you can go back to your bucket and pour-off some more material into a new cup or container, add accelerator to that; and then follow the same procedure over and over again as many times as necessary. You will want to get two coats on everywhere. It doesn't matter if one area sets-up completely and you butt up against it with another batch. The important thing to remember is not to brush over a new area of the mold, if the material in your cup is getting too thick; because you won't get good surface contact. If it starts to get too thick, throw it out; and, on the next batch, add less accelerator. If you still have some of your original mix left over (without accelerator), you can use this for dipping and soaking your fiberglass. It is not a good idea to add accelerator to that because you won't have enough working time. Without accelerator, the Forton mix wil start to gel after about 35-40- minutes, and it will no longer be workable after 40-minutes. So, unlike plaster, Forton does not thicken-up slowly. Nothing will happen for the first 35-minutes. Everything starts to change after about 35-minutes. This is really quite ideal. The only thing that may occur with a bucket of Forton mix before the 35-minutes has gone by, is that sometimes a thin skin will form on the surface, due to exposure to the air. If that occurs, you can just take a spatula and skim it off.
You don't have to mix a full batch (as described above); you can mix even tiny batches, so long as you observe the correct ratios of all the components. So, you can use this system for mixing small batches for filling areas like seams, if you need to. Any area that you fill should afterwards be sanded with waterproof sandpaper (dipped in water), within a few minutes; because, otherwise, when Forton is fully set, it becomes extremely hard.You can accelerate small mixes of Forton to the point where they become thick immediately, like a fine putty.