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Shipping Information:
- Ships via UPS only.
- Usually ships in 1-2 business days.
Polytek Polyurethane Mold Rubber: 74-Series: 74-45
- Create your own custom molds using a professional, high-quality molding rubber.
- The 74-45 Mold Rubber is a 45 shore polyurethane, with medium flexiblility.
- 30 minute pour time. Cures in 16-24 hours.
- Poly 74-45 liquid rubber is an excellent multi-purpose, economical mold
material that will provide long mold life, durability and consistent
performance under repeated casting.
- Poly 74-45 is popular for casting
decorative architectural concrete panels and accessories.
- Mix Ratio is 1A:1B for this product (you mix equal weights of part A and part B).
- Poly 74-45 is available in kits that net weights of: 4 lbs, 16 lbs, 80 lbs, and drums of 900 lbs.
- Mold Rubber MUST be mixed by weight, using a scale such as these sold on Amazon.com for around $70.00.
- Can be pigmented using PolyColors (sold separately) coloring dyes.
- Download: Poly 74 Series Instruction Guide: TDS.
- Download: Poly 74 Series Safety Data Sheet: Part A MSDS. Part B MSDS.
How Much Mold Rubber Do You Need?
- Mold Rubbers have different specific volume amounts that 1 lb. of material creates. All Poly 74 Series rubber have a specific volume of 27.5 in³, which is roughly a 3" x 3" cube (3" x 3" x 3" = 27 in³)
- Estimating How Much Rubber You Need:
- 1. Calculate the volume of the total mold box/cylinder in cubic inches.
- For a box: V = L x W x H
- For a cylinder: V = π x r² x H
- Where: L = Length, W = Width, H = Height, π = 3.14, r = Radius
- 2. If molding a model/object, estimate the volume of the object.
- 3. Subtract the estimated volume of the model from the volume of the mold box/cylinder.
- 4. Divide the result (volume of mold area) by specific volume of the mold rubber to determine the lbs. of mold rubber needed.
- Example: The volume of a rectangular mold box: 10 in x 5 in x 5 in = 250 in³
- The volume of the model/object : 8 in x 3 in x 3 in = 72 in³
- Subtract the volume of the model from the volume of the mold box: 250 in³ - 72 in³ = 178 in³
- Divide by the specific volume of Poly 74-45 Liquid Rubber (27.5 in³/lb): 178 in³ ÷ 27.5 in³/lb = 6.5 lbs. Rubber
About Polyurethane Mold Rubbers by Polytek:
- Poly 74 Series of Mold Rubber is Polytek’s easiest-to-use and most versatile mold rubbers. Ranging from soft 74-20 (A20 shore value) to mid-range hardness 74-45 (A45 shore value), the 74 Series of mold rubbers are popular with plaster casters, concrete precasters and art foundries. Can be poured as supplied, or made brushable by mixing in Poly Fiber II (sold separately).
- Polytek has many mold-making products, ranging from polyurethanes, plastics, silicones, resins, sculptures, foams, etc., and some of their products may not be on our website. Please contact us if you need a Polytek product that we don't currently have listed, but that is in the Polytek Catalog, or on their website: www.polytek.com, and we will get you the best price possible for it.
- Cast Concrete Urethane Rubber Product Recommendations:
- Poly 74-20: Veneer Stone, Intricate Architectural Elements
- Poly 74-45: Decorative Architectural Elements, Decorative Concrete Edging
- Poly 75-60: Concrete Sink Molds, Plugs, Edging, Simple Architectural Elements, Flex/Floppy Stamping Mats
- Poly 75-65: Form Liners, Paver Molds
- Poly 75-70: Form Liners
- Poly 75-80: Form Liners, Stamping Mats
- Shore hardness determines how flexible the rubber is when cured. A lower number means more flexible, which will usually allow the rubber to make molds that are more intricate and detailed, where the rubber can form 'around' objects better and peel off easier when done. Higher numbers are more rigid, which provides greater durability for long term use of the mold.
 Using Mold Rubber:
- Please refer to the TDS Instruction Sheet above for all mixing and application information.
- Pol-Ease 2300 (sold separately) is an aerosol release that should be used on any surface the rubber is poured onto, during mold making, to prevent sticking.
- Pol-Ease 2650 (sold separately)
is an silicone-free release that should be used on the rubber molds
when casting concrete or plaster, to prevent concrete from sticking to
the mold. Pol-Ease 2300 will also work to prevent concrete from
sticking to the rubber mold, but may create a shiny surface on the
concrete.
- PolyCoat (sold separately)
should be used to seal non-rubber surfaces (such as wood, concrete,
tile, rock, etc.) before molding off it, or to treat Polyurethane Molds
that will have repeated molds made from that master- without needing to
apply a release every time.
- Polyplasticine Clay (sold separately) that is sulfur free should be used to seal off the molds when pouring mold rubber.
Storage Information:
- Material should be stored at room temperature (@ 75°F) for 24 hours prior to use.
- Shelf life of the liquid rubber components is approx. 6 months. Air and humidity is the largest factor in making the material go bad, so care should be taken to immediately re-close the containers after pouring out any material. It is strongly recommended to use PolyPurge (sold separately) each time a container is opened/closed: PolyPurge is a heavier-than-air dry gas that when sprayed for a few seconds into the container, will create a barrier between any air moisture and the polyurethane rubber product.
- Polyurethane molds should be stored flat to avoid deforming over time, and kept out of sunlight. Any molds that will be used in occasional sunlight should be made using UV Additive (sold separately) when mixing the rubber, to help the mold resist UV damage.
Shipping Information:
- Usually ships within 2-3 business days, via UPS Ground or by various Freight carriers.
- Most orders totaling $8,000 or more of Polytek molding products will qualify for free Freight (to Continental US only)
Using Poly 74-45 to Make Barn Wood Mold (Part 1 of 3)
Using Poly 74-45 to Make Barn Wood Mold (Part 2 of 3)
Using Poly 74-45 to Make Barn Wood Mold (Part 3 of 3)
Selecting Mold Rubber Hardness
- Re-usable Edge Form to create a realistic Rock Edge on concrete.
- "Granite Rock" edge detail, 2 1/2" tall.
- This form is designed to be used right in place to make pool surround edging, cast in-place concrete countertops, bars, fireplace hearths, seating benches, and more.
- Made of extremely durable polyurethane that can flex and stay strong.
- Cut to length easily with a utility knife or chop saw. Join cut pieces using silicone.
- Good for hundreds of uses- Actually gets better with each use as they 'season'.
- Quantity discounts automatically will reflect when added to a cart. Click the Quantity Discounts button above to see the pricing.
Product Specifications: - Measurements:
- Rock Edge portion: 89 1/4"L x 2 1/2"H.
- Overall Rubber Liner: 5 7/8"H x 89 1/4"L x 1 5/8"Thick
- Weight: 26 lbs.
Mold Setup: - The Pool Rock Edge Form Liner can be curved to form a radius edge, about an 18" Radius. If the Edge Form
Liner begins to ripple and distort, then the radius is too tight, so you
will need to make the curve radius larger to ensure a smooth,
consistent edge detail.
- Edge Form Liners can be cut to fit your
form. Cut using a SHARP razor knife, or with a chop saw. Liners can be
cut straight, or mitered at angles.
- This Rock Edge Liner is
designed to be secured in place by screwing through the thick bottom
part of the rubber. Use washers with the screws to keep the screw head
from sinking into the rubber.
- Use
of a Rubber Safe form release is recommended, but usually not required. Form release will create a smoother finish on the
concrete, less air pockets in the concrete edge, and easier to clean the
Edge Form Liners when finished.
- Vibrate concrete well (either
vibrating the concrete, or rapidly tapping the edges of the forms with a
hammer or palm sander), or use your fingers to compact the concrete
against the Form Liner to remove as many air pocket voids as possible.
Edge Liner Removal:- After
the concrete is sufficiently set up, remove the Edge Form Liner by
slowly pulling it away, starting on one end and working down the length
of the Edge Liner.
- If
the Edge Form Liner needs to be removed before the concrete is cured
(usually only when using on cast in place concrete, such as steps or
pool decks), make sure to remove edge slowly, evenly pulling the liner
'out' away from the concrete.
- Concrete may will have small 'bumps' which can be sanded off with a 200 grit
sandpaper. These bumps tend to disappear the more the Edge Form Liner
is used, as it becomes seasoned.
- Fill any air pocket voids with a Cement Slurry Mix.
Edge Liner Care:- Clean
with a stiff brush and water after each use. Any silicone left on the
forms should be peeled or scraped off (the sooner the easier to remove).
Any hardened concrete and difficult to remove silicone can usually be
removed using a wire brush.
- Muriatic Acid can be used to clean
of cement residue from the Edge Form Liners in a 20:1 ratio (20 parts
water to 1 part muriatic acid). Rub the Edge Form Liner with a stiff
nylon brush and the muriatic acid water. Rinse Form Liner thoroughly
with clean water.
- Store Edge Form Liners out of direct sunlight, laid out flat.
- If
Edge Form Liners ever get curved or twisted so they don't lay flat
naturally, the easiest solution is to lay them out flat on a concrete or
asphalt surface on a really hot day and let the sun heat them up,
straighten them out, and then when they cool they should hold their
shape more naturally.
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Product Description:
