Rubber Repair Compounds | McMaster-Carr

	Hardness Hardness

	Hardness Rating Hardness Rating

	Color Color

	Light Brown		Green
	Blue		Dark Gray
	Light Blue		Amber
	Yellow		Beige
	Black		Clear
	Gray		Orange
	White

	Material Material

Rubber

Foam

Aluminum-Filled Urethane

Plastic

	Weight Weight

	Time to Cure Time to Cure

	Shrinkage Shrinkage

	Maximum Temperature Maximum Temperature

	Time to Demold Time to Demold

	Volume Volume

250 cu. in. or greater

	Mixing Required Mixing Required

Yes

	Time to Harden Time to Harden

	Cure Temperature Cure Temperature

	RoHS (Restriction of Hazardous Substances) RoHS (Restriction of Hazardous Substances)

RoHS Compliant

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

DFARS Specialty Metals
COTS-Exempt

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	Component Component

Casting Compound

Casting Compound with
Dispensing Gun

	Cell Type Cell Type


Open	Closed

	Density Density

	Flexibility Flexibility

Flexible

Rigid

	Specifications Met Specifications Met

FDA Compliant 21 CFR
175.105

FDA Compliant 21 CFR
177.1680

	Foam Expansion Foam Expansion

	Machinable Machinable

Yes

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63 Products

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°	0.1%	Light Brown	Yes	25	1	0000000	000000
Durometer 20A	15 min.	168 hrs.	5 hrs.	77°	180°	0.1%	Light Brown	Yes	250	10	0000000	000000
Firm
Durometer 40A	15 min.	168 hrs.	5 hrs.	77°	180°	0.1%	Light Brown	Yes	25	1	0000000	00000
Durometer 40A	15 min.	168 hrs.	5 hrs.	77°	180°	0.1%	Light Brown	Yes	250	10	0000000	000000
Durometer 60A	15 min.	168 hrs.	2 hrs.	77°	180°	0.1%	Light Brown	Yes	25	1	0000000	00000
Durometer 60A	15 min.	168 hrs.	2 hrs.	77°	180°	0.1%	Light Brown	Yes	250	10	0000000	000000
Hard
Durometer 80A	15 min.	168 hrs.	3 hrs.	77°	180°	0.1%	Light Brown	Yes	6	1/4	0000000	00000
Durometer 80A	15 min.	168 hrs.	3 hrs.	77°	180°	0.1%	Light Brown	Yes	25	1	0000000	00000
Durometer 80A	15 min.	168 hrs.	3 hrs.	77°	180°	0.1%	Light Brown	Yes	250	10	0000000	000000
Durometer 94A	15 min.	168 hrs.	2 hrs.	77°	180°	0.1%	Light Brown	Yes	25	1	0000000	00000
Durometer 94A	15 min.	168 hrs.	2 hrs.	77°	180°	0.1%	Light Brown	Yes	250	10	0000000	000000
Durometer 60D	15 min.	168 hrs.	2 hrs.	77°	180°	0.1%	Light Brown	Yes	25	1	0000000	00000
Durometer 60D	15 min.	168 hrs.	2 hrs.	77°	180°	0.1%	Light Brown	Yes	250	10	0000000	000000
Durometer 85D	5 min.	2 hrs.	1.5 hrs.	77°	180°	0.1%	Green	Yes	80	5	000000	00000
Durometer 85D	5 min.	2 hrs.	1.5 hrs.	77°	180°	0.1%	Green	Yes	320	20	000000	000000

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.

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

Acrylic Casting Compound

Silicone Casting Compound

Acrylic
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 85D	2 min.	11 min.	11 min.	69°	350°	0%	Light Blue	Yes	20	1	0000000	0000000
Durometer 85D	2 min.	11 min.	11 min.	69°	350°	0%	Light Blue	Yes	62	3	0000000	000000
Silicone
Soft
Durometer 27A	2 min.	15 min.	15 min.	70°	650°	0%	Light Blue	Yes	4	0.2	0000000	00000
Durometer 27A	2 min.	15 min.	15 min.	70°	650°	0%	Light Blue	Yes	46	2.2	0000000	000000
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	000000
Durometer 50A	2 min.	10 min.	10 min.	69°	250°	0%	Light Blue	Yes	13	0.8	0000000	000000
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

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°	Not Rated	Dark Gray	Yes	25	1	0000000	000000
Durometer 60A	15 min.	168 hrs.	3 hrs.	75°	180°	Not Rated	Dark Gray	Yes	100	4	0000000	000000
Hard
Durometer 85A	15 min.	168 hrs.	3 hrs.	75°	180°	Not Rated	Black	Yes	25	1	0000000	00000
Durometer 85A	15 min.	168 hrs.	3 hrs.	75°	180°	Not Rated	Black	Yes	100	4	0000000	000000

See-Through Casting Compounds

Create transparent molds to monitor fill levels, differentiate parts at a glance, and avoid damaging parts when cutting the mold away. These casting compounds are two parts that activate when mixed.

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 required, 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 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 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°	0.8%	Clear	Yes	25	1	0000000	000000
Durometer 75D	6 min.	144 hrs. @ 77° F	2 hrs. @ 77° F	180°	0.8%	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	000000

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. Cast up to 1/2" in thickness at a time.

View our selection of release agents. View additional information about the hardness of this material.

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 80D	20 min.	168 hrs.	4 hrs.	72°	134°	0.3%	White	Yes	49	2	0000000	000000
Durometer 80D	20 min.	168 hrs.	4 hrs.	72°	134°	0.3%	White	Yes	395	16	00000000	000000

Machinable Casting Compounds

After these compounds cure, they're tough enough to be machined. 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.

Aluminum-Filled 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 84D	6 min.	168 hrs.	90 min.	72°	130°	1.5%	Gray	Yes	72 1/2	5	00000000	0000000
Durometer 84D	6 min.	168 hrs.	90 min.	72°	130°	1.5%	Gray	Yes	290	20	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°	0%	Blue	Yes	22	1	0000000	000000
Durometer 65A	120 min.	24 hrs.	16 hrs.	78°	400°	0%	Blue	Yes	242	11	0000000	000000

Long-Life Casting Compounds

Create rubber molds that retain their shape for decades—they won’t soften, degrade, or warp, so you can continue to replicate intricate parts. Because these compounds don’t shrink as they cure, they are more accurate and predictable than other compounds.

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	0000000

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%	Amber	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%	Amber	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%	Amber	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%	Amber	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%	Amber	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%	Amber	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	0000000	00000

Foam Casting Compounds

Step 1. Pour compound into your mold.

Step 2. Compound
expands to fill every
hole and cavity.

Create lightweight molds with these two-part compounds. They expand as foam after they’re poured to fill every cavity. The denser the foam, the less it will expand. Before casting, apply petroleum jelly (not included) to prevent sticking, stretching, and tearing. It won't cause the foam to collapse as it cures.

Flexible compounds cure into soft, open-cell foam, which absorbs water, air, and gases. They are often used to cast gaskets, cushions, and other bendable objects.

Rigid compounds form stiff, closed-cell foam, which prevents water and air from flowing through the part. Machinable, they’re dense enough to create prototype modeling blocks, so you can test setups without wearing down tools.

Polyurethane Foam
Foam Expansion	Density, lbs./cu. ft.	Time to Harden	Time to Cure	Time to Demold	Cure Temperature, °F	Max. Temperature, °F	Shrinkage	Color	Mixing Required	Weight, lbs.		Each
Flexible
4 times	12	3 min.	25 min.	25 min.	80°	125°	Not Rated	White	Yes	12	0000000	0000000
4 times	12	3 min.	25 min.	25 min.	80°	125°	Not Rated	White	Yes	3	00000000	00000
8 times	8	3 min.	25 min.	25 min.	80°	125°	Not Rated	White	Yes	12	0000000	000000
8 times	8	3 min.	25 min.	25 min.	80°	125°	Not Rated	White	Yes	3	00000000	00000
15 times	4	3 min.	25 min.	25 min.	80°	125°	Not Rated	White	Yes	12	0000000	000000
15 times	4	3 min.	25 min.	25 min.	80°	125°	Not Rated	White	Yes	3	00000000	00000
Rigid—Machinable
2 times	20	3 min.	15 min.	15 min.	75°	85°	Not Rated	Beige	Yes	16	0000000	000000
7 times	12	3 min.	15 min.	15 min.	75°	85°	Not Rated	Beige	Yes	16	0000000	000000
7 times	12	3 min.	15 min.	15 min.	75°	85°	Not Rated	Beige	Yes	4	00000000	00000
19 times	4	3 min.	15 min.	15 min.	75°	85°	Not Rated	Beige	Yes	16	0000000	000000
19 times	4	3 min.	15 min.	15 min.	75°	85°	Not Rated	Beige	Yes	4	00000000	00000