Rubber Molds | McMaster-Carr

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	Hardness Hardness

Durometer 20A

Durometer 27A

	Hardness Rating Hardness Rating

Soft

Firm

Hard

	Material Material	Show

Rubber

Silicone Rubber

Urethane Rubber

	Material Material	Hide

	Color Color

	White		Light Blue
	Black		Blue
	Green		Yellow
	Blue- Green		Clear
	Orange

	Shrinkage Shrinkage

0.5%

1.5%

	Maximum Temperature Maximum Temperature

Less than 250° F

250° to 499° F

500° to 999° F

	Time to Harden Time to Harden

	Time to Cure Time to Cure

	Weight Weight

Less than 10 lbs.

10 to 14.9 lbs.

20 to 49.9 lbs.

	Cure Temperature Cure Temperature

	Volume Volume

Less than 100 cu. in.

100 to 249 cu. in.

250 to 499 cu. in.

	Mixing Required Mixing Required

Yes

	Component Component

Casting Compound

Casting Compound with
Dispensing Gun

	Time to Demold Time to Demold

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	Clarity Clarity

Clear

	Specifications Met Specifications Met

FDA Compliant 21 CFR
175.105

FDA Compliant 21 CFR
177.1680

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50 Products

Fast-Setting Casting Compounds

Create detailed rubber shapes that are ready to use in fifteen minutes or less. Unlike traditional casting compounds, which can take up to 24 hours to set, these compounds harden after two minutes, and can be removed from molds within fifteen. Use them to make your own prototypes, molds, and linings.

Combine acrylic or silicone with a 69° cure temperature compounds in different ratios to adjust the consistency from thin to thick. Thin mixtures are easier to pour and better for filling small crevices. Thick mixtures will shrink less as they dry.

Silicone with a 70° cure temperature compounds are a putty that you can mix with your hands and form into any shape. Press an object into these compounds to create a mold for casting duplicates. They do not shrink as they dry, so textures and other fine details are captured faithfully. Soft silicone is more flexible and easier to peel off of molds than firm silicone, especially when making complex shapes.Firm silicone holds its shape better than soft silicone, so small ridges and channels are less likely to collapse or deform while making molds.

Compounds with dispenser gun come ready to use—no mixing required—and won’t leave a mess.

Casting Compounds

Silicone Casting Compound

Silicone
Hardness	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Volume, cu. in.	Weight, lbs.		Each
Soft
Durometer 27A	2 min.	15 min.	15 min.	70°	650°	0%	Light Blue	Yes	4	0.2	0000000	000000
Durometer 27A	2 min.	15 min.	15 min.	70°	650°	0%	Light Blue	Yes	46	2.2	0000000	00000
Durometer 30A	2 min.	10 min.	10 min.	69°	250°	0%	Green	Yes	8	0.5	0000000	00000
Durometer 30A	2 min.	10 min.	10 min.	69°	250°	0%	Green	Yes	23	1.1	0000000	000000
Firm
Durometer 40A	2 min.	15 min.	15 min.	70°	600°	0%	Green	Yes	4	0.2	0000000	00000
Durometer 40A	2 min.	15 min.	15 min.	70°	600°	0%	Green	Yes	46	2.2	0000000	00000
Durometer 50A	2 min.	10 min.	10 min.	69°	250°	0%	Light Blue	Yes	13	0.8	0000000	00000
Durometer 50A	2 min.	10 min.	10 min.	69°	250°	0%	Light Blue	Yes	32	1.75	0000000	000000

Casting Compounds with Dispensing Gun

Silicone Casting Compound with Dispensing Gun

Silicone
Hardness Rating	Hardness	Time to Harden	Time to Cure	Time to Demold	Color	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Mixing Required	Weight, lbs.	Includes		Each
Soft	Durometer 30A	2 min.	10 min.	10 min.	Green	69°	250°	0%	No	4	Carrying Case, Six each 3 cu. in. Disposable Cartridges	0000000	0000000
Soft Firm	Durometer 30A Durometer 55A	2 min. 2 min.	10 min. 6 min.	10 min. 6 min.	Green Orange	69°	250°	0%	No	4	Carrying Case, Six each 3 cu. in. Disposable Cartridges	0000000	000000
Firm	Durometer 55A	2 min.	6 min.	6 min.	Orange	69°	250°	0%	No	4	15 Disposable Nozzles, 2 Snap-On Nozzles, Carrying Case, Six each 3 cu. in. Disposable Cartridges	0000000	000000

Replacement Nozzles for Casting Compounds with Dispensing Gun

Replacement Nozzle

Nozzle Style	Pkg. Qty.		Pkg.
Angled	15	0000000	000000
Straight	15	0000000	00000

Replacement Cartridges for Casting Compounds with Dispensing Gun

Replacement Cartridge

Color	Volume		Each
Green	3 cu. in.	0000000	000000
Orange	3 cu. in.	0000000	00000

Casting Compounds

Capture intricate details when creating prototypes, molds, and linings with these easy-to-mix two-part compounds. This urethane is water and abrasion resistant.

View our selection of release agents. View additional information about the hardness of these materials.

Urethane
Hardness	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Volume, cu. in.	Weight, lbs.		Each
Soft
Durometer 20A	15 min.	168 hrs.	5 hrs.	77°	180°	1.5%	Black	Yes	25	1	0000000	000000
Durometer 20A	15 min.	168 hrs.	5 hrs.	77°	180°	1.5%	Black	Yes	250	10	0000000	000000
Firm
Durometer 40A	15 min.	168 hrs.	5 hrs.	77°	180°	1.5%	Black	Yes	25	1	0000000	00000
Durometer 40A	15 min.	168 hrs.	5 hrs.	77°	180°	1.5%	Black	Yes	250	10	0000000	000000
Durometer 60A	15 min.	168 hrs.	2 hrs.	77°	180°	0.5%	Black	Yes	25	1	0000000	00000
Durometer 60A	15 min.	168 hrs.	2 hrs.	77°	180°	0.5%	Black	Yes	250	10	0000000	000000
Hard
Durometer 80A	15 min.	168 hrs.	3 hrs.	77°	180°	1.5%	Black	Yes	6	1/4	0000000	00000
Durometer 80A	15 min.	168 hrs.	3 hrs.	77°	180°	1.5%	Black	Yes	25	1	0000000	00000
Durometer 80A	15 min.	168 hrs.	3 hrs.	77°	180°	1.5%	Black	Yes	250	10	0000000	000000
Durometer 94A	15 min.	168 hrs.	2 hrs.	77°	180°	1.5%	Black	Yes	25	1	0000000	00000
Durometer 94A	15 min.	168 hrs.	2 hrs.	77°	180°	1.5%	Black	Yes	250	10	0000000	000000
Durometer 60D	15 min.	168 hrs.	2 hrs.	77°	180°	1.5%	Black	Yes	25	1	0000000	00000
Durometer 60D	15 min.	168 hrs.	2 hrs.	77°	180°	1.5%	Black	Yes	250	10	0000000	000000
Durometer 85D	5 min.	2 hrs.	1.5 hrs.	77°	180°	1.5%	Blue-Green	Yes	80	5	000000	00000
Durometer 85D	5 min.	2 hrs.	1.5 hrs.	77°	180°	1.5%	Blue-Green	Yes	320	20	000000	000000

See-Through Casting Compounds

These compounds make transparent molds, so you can monitor the fill level, identify molds after casting, and avoid damaging parts when cutting the mold away. All are two-part compounds; mix together to activate.

Urethane compounds create hard molds, which are good for delicate and intricate shapes because the small contours won't deform or collapse when the material is poured in. Although not necessary, curing urethane molds inside a vacuum chamber improves their clarity. By removing trapped air bubbles, the chamber prevents the finished mold from looking speckled.

Silicone compounds handle much higher temperatures than urethane compounds—up to 570° F. Silicone also cures faster than urethane, and it won't shrink as it cures, which means you won't need to guess at the final size of your mold. Because silicone compounds trap a lot of air bubbles when mixed, they must be cured inside a vacuum chamber. The chamber removes the trapped air bubbles, strengthens the mold, and improves its clarity.

View our selection of release agents. View additional information about the hardness of these materials.

Urethane
Hardness	Time to Harden	Time to Cure	Time to Demold	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Volume, cu. in.	Weight, lbs.		Each
Hard
Durometer 80A	6 min.	144 hrs. @ 77° F	2 hrs. @ 77° F	180°	5%	Clear	Yes	25	1	0000000	000000
Durometer 75D	6 min.	144 hrs. @ 77° F	2 hrs. @ 77° F	180°	5%	Clear	Yes	25	1	0000000	00000
Silicone Rubber
Firm
Durometer 40A	10 min.	1.5 hrs. @ 77° F, 30 min. @ 120° F	1.5 hrs. @ 77° F, 30 min. @ 120° F	570°	0%	Blue	Yes	57	2.2	0000000	00000

Easy-to-Work Casting Compounds

Combine the liquid components to form a putty that can be molded into or around any shape. Use these compounds to capture intricate details when creating prototypes, molds, and linings.

View our selection of release agents. View additional information about the hardness of these materials.

Urethane
Hardness	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Volume, cu. in.	Weight, lbs.		Each
Firm
Durometer 60A	15 min.	168 hrs.	3 hrs.	75°	180°	1.5%	Black	Yes	25	1	0000000	000000
Durometer 60A	15 min.	168 hrs.	3 hrs.	75°	180°	1.5%	Black	Yes	100	4	0000000	00000
Hard
Durometer 85A	15 min.	168 hrs.	3 hrs.	75°	180°	1.5%	Black	Yes	25	1	0000000	00000
Durometer 85A	15 min.	168 hrs.	3 hrs.	75°	180°	1.5%	Black	Yes	100	4	0000000	00000

Fine-Detail Casting Compounds

Replicate even the most complex details when creating prototypes, molds, and linings. This easy-to-mix two-part compound flows smoothly into crevices.

View our selection of release agents. View additional information about the hardness of these materials.

Urethane
Hardness	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Volume, cu. in.	Weight, lbs.		Each
Hard
Durometer 83D	8 min.	168 hrs.	2 hrs.	75°	135°	1.5%	White	Yes	94	3.6	00000000	000000
Durometer 83D	8 min.	168 hrs.	2 hrs.	75°	135°	1.5%	White	Yes	374	14.4	00000000	000000

Chemical-Resistant Casting Compounds

This silicone compound offers good resistance to acids, oils and salt water. Use it to capture intricate details when creating prototypes, molds, and linings with this easy-to-mix two-part compound. It is a durable and tear-resistant silicone, which easily demolds.

View our selection of release agents. View additional information about the hardness of these materials.

Silicone
Hardness	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Volume, cu. in.	Weight, lbs.		Each
Firm
Durometer 65A	120 min.	24 hrs.	16 hrs.	78°	400°	1.5%	Blue	Yes	22	1	0000000	000000
Durometer 65A	120 min.	24 hrs.	16 hrs.	78°	400°	1.5%	Blue	Yes	242	11	0000000	000000

Long-Life Casting Compounds

Create rubber molds that keep their shape and strength for decades. Formulated to last longer than other casting compounds, these compounds produce molds that won’t soften and degrade so you can cast the same intricate part every time. Since these are two-part compounds, they must be mixed together to activate. Unlike other casting compounds, they won’t shrink during curing for accurate, predictable results.

View our selection of release agents. View additional information about the hardness of these materials.

Urethane
Hardness	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Volume, cu. in.	Weight, lbs.		Each
Firm
Durometer 45A	60 min.	24 hrs.	16 hrs.	77°	200°	0%	Yellow	Yes	58	2.2	0000000	000000

Food Industry Casting Compounds

These food-grade compounds comply with FDA 21 CFR. They are easy-to-mix two-part compounds that capture intricate details when creating prototypes, molds, and linings.

View our selection of release agents. View additional information about the hardness of these materials.

Urethane
Hardness	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Specifications Met	Volume, cu. in.	Weight, lbs.		Each
Firm
Durometer 60A	8 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	0000000	000000
Durometer 60A	8 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	250	10	0000000	000000
Hard
Durometer 78A	4 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	0000000	00000
Durometer 78A	4 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	250	10	0000000	000000
Durometer 88A	4 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	0000000	00000
Durometer 88A	4 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	250	10	0000000	000000
Durometer 75D	5 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	0000000	00000
Durometer 75D	5 min.	12 hrs.	2 hrs.	120°	180°	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	250	10	0000000	000000