Rubber Molds | McMaster-Carr

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Time to Cure

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25 cu. in. to 49.9 cu. in.

50 cu. in. to 99.9 cu. in.

100 cu. in. to 249.9 cu. in.

250 cu. in. or greater

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Casting Compound with Dispensing Gun

Time to Harden

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Cure Temperature

Mixing Required

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Export Control Classification Number (ECCN)

EAR99

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

For Use On

62 Products

Quick-Set 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.

Casting Compounds

Silicone Rubber

Soft—Soft silicone rubber is more flexible and easier to peel off of molds than medium silicone rubber, especially when making complex shapes.

Medium—Medium silicone rubber holds its shape better than soft silicone rubber, so small ridges and channels are less likely to collapse or deform while making molds.

69° F Cure Temperature—Combine acrylic plastic or silicone rubber 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.

70° F Cure Temperature—Silicone rubber 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.

	Time to Demold, min.	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Volume, cu. in.	Wt., lb.		Each
Silicone Rubber







	Soft

	Durometer 27A	2	15	15	70	650	0%	Light Blue	Yes	4	0.2	8595K15	000000


	Durometer 27A	2	15	15	70	650	0%	Light Blue	Yes	46	2.2	8595K14	000000
	Durometer 30A	2	10	10	69	250	0%	Green	Yes	8	0.5	5166N14	00000
	Durometer 30A	2	10	10	69	250	0%	Green	Yes	23	1.1	5166N15	000000




			Medium

			Durometer 40A	2	15	15	70	600	0%	Green	Yes	4	0.2	8595K12	00000


			Durometer 40A	2	15	15	70	600	0%	Green	Yes	46	2.2	8595K13	000000
			Durometer 50A	2	10	10	69	250	0%	Light Blue	Yes	13	0.8	5166N16	000000
			Durometer 50A	2	10	10	69	250	0%	Light Blue	Yes	32	1.75	5166N17	000000

Casting Compounds with Dispensing Gun

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

Soft—Soft silicone rubber is more flexible and easier to peel off of molds than medium silicone rubber, especially when making complex shapes.

Medium—Medium silicone rubber holds its shape better than soft silicone rubber, so small ridges and channels are less likely to collapse or deform while making molds.

	Hardness	Time to Harden, min.	Time to Cure	Time to Demold	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Wt., lb.	Includes		Each
Silicone Rubber



	Soft	Durometer 30A	2	10 min.	10 min.	69	250	0%	Green	No	4	Carrying Case, Six each 3 cu. in. Disposable Cartridges	5166N13	0000000


	Soft Medium	Durometer 30A Durometer 55A	2	10 min. 6 min.	10 min. 6 min.	69	250	0%	Green Orange	No	4	Carrying Case, Six each 3 cu. in. Disposable Cartridges	5166N12	000000
	Medium	Durometer 55A	2	6 min.	6 min.	69	250	0%	Orange	No	4	15 Disposable Nozzles, 2 Snap-On Nozzles, Carrying Case, Six each 3 cu. in. Disposable Cartridges	5166N11	000000

Replacements for Casting Compounds

Nozzle Type	Pkg. Qty.		Pkg.
Angled	15	5166N21	000000
Straight	15	5166N22	00000

Color	Volume, cu. in.		Each
Green	3	5166N18	000000
Orange	3	5166N19	00000

Casting Compounds

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

View our selection of release agents.

	Time to Demold, hr.	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Volume, cu. in.	Wt., lb.		Each
Urethane Rubber







	Soft

	Durometer 20A	15	168	5	77	180	0.1%	Black	Yes	25	1	8644K51	000000


	Durometer 20A	15	168	5	77	180	0.1%	Black	Yes	250	10	8644K52	000000




			Medium

			Durometer 40A	15	168	5	77	180	0.1%	Black	Yes	25	1	8644K53	00000


			Durometer 40A	15	168	5	77	180	0.1%	Black	Yes	250	10	8644K54	000000
			Durometer 60A	15	168	2	77	180	0.1%	Black	Yes	25	1	8644K24	00000
			Durometer 60A	15	168	2	77	180	0.1%	Black	Yes	250	10	8644K26	000000
			Durometer 60D	15	168	2	77	180	0.1%	Black	Yes	25	1	8644K55	00000
			Durometer 60D	15	168	2	77	180	0.1%	Black	Yes	250	10	8644K56	000000




					Hard

					Durometer 80A	15	168	3	77	180	0.1%	Black	Yes	25	1	8644K11	00000


					Durometer 80A	15	168	3	77	180	0.1%	Black	Yes	250	10	8644K12	000000
					Durometer 94A	15	168	2	77	180	0.1%	Black	Yes	25	1	8644K18	00000
					Durometer 94A	15	168	2	77	180	0.1%	Black	Yes	250	10	8644K19	000000
					Durometer 75D	15	168	2	77	180	0.1%	Black	Yes	25	1	8690K311	00000
					Durometer 75D	15	168	2	77	180	0.1%	Black	Yes	250	10	8690K312	000000
					Durometer 85D	5	2	1.5	77	180	0.1%	Green	Yes	80	5	8690K1	00000
					Durometer 85D	5	2	1.5	77	180	0.1%	Green	Yes	320	20	8690K2	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.

View our selection of release agents.

Urethane Rubber—Urethane rubber compounds are tougher than silicone rubber compounds, so your molds will last longer. Although not required, curing urethane rubber molds inside a vacuum chamber improves their clarity. By removing trapped air bubbles, the chamber prevents the finished mold from looking speckled.

Silicone Rubber—Silicone rubber compounds handle higher temperatures than urethane rubber compounds—up to 570° F. Silicone rubber also cures faster than urethane rubber, 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 rubber 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.

	Time to Demold	Cure Temp.	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Volume, cu. in.	Wt., lb.		Each
Urethane Rubber







	Medium

	Durometer 40A	6	144 hr.	2 hr.	77° F	180	0.8%	Clear	Yes	25	1	4431N101	000000


	Durometer 60A	6	144 hr.	2 hr.	77° F	180	0.8%	Clear	Yes	25	1	4431N102	00000




			Hard

			Durometer 80A	6	144 hr.	2 hr.	77° F	180	0.8%	Clear	Yes	25	1	8644K59	00000


			Durometer 75D	6	144 hr.	2 hr.	77° F	180	0.8%	Clear	Yes	25	1	8644K58	00000


			Silicone Rubber







							Medium

							Durometer 40A	10	1.5 hr. 30 min.	1.5 hr. 30 min.	77° F 120° F	570	0%	Blue	Yes	57	2.2	8644K63	000000

Chemical-Resistant Casting Compounds

This silicone rubber 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 rubber, which easily demolds.

View our selection of release agents.

	Time to Demold, hr.	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Volume, cu. in.	Wt., lb.		Each
Silicone Rubber







	Medium

	Durometer 65A	120	24	16	78	400	0%	Blue	Yes	22	1	8595K77	000000


	Durometer 65A	120	24	16	78	400	0%	Blue	Yes	242	11	8595K11	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.

	Time to Demold, hr.	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Volume, cu. in.	Wt., lb.		Each
Urethane Rubber







	Medium

	Durometer 45A	60	24	16	77	200	0%	Yellow	Yes	58	2.2	4353N11	0000000

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.

	Time to Demold, hr.	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Volume, cu. in.	Wt., lb.		Each
Urethane Rubber







	Hard

	Durometer 80D	20	168	4	72	134	0.3%	White	Yes	49	2	87075K6	000000


	Durometer 80D	20	168	4	72	134	0.3%	White	Yes	395	16	87075K61	000000

Food and Beverage 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.

	Time to Demold, hr.	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Food Industry Std.	Volume, cu. in.	Wt., lb.		Each
Urethane Rubber







	Medium

	Durometer 40A	8	12	2	120	180	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	8644K71	000000


	Durometer 60A	8	12	2	120	180	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	8644K34	00000
	Durometer 60A	8	12	2	120	180	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	250	10	8644K33	000000




			Hard

			Durometer 78A	4	12	2	120	180	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	8644K37	00000


			Durometer 88A	4	12	2	120	180	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	8644K41	00000
			Durometer 88A	4	12	2	120	180	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	250	10	8644K43	000000
			Durometer 75D	5	12	2	120	180	5%	White	Yes	FDA Compliant 21 CFR 175.105, FDA Compliant 21 CFR 177.1680	25	1	8644K47	00000

Easy-Form 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.

	Time to Demold, hr.	Cure Temp., ° F	Max. Temp., ° F	Shrinkage	Color	Mixing Req.	Volume, cu. in.	Wt., lb.		Each
Urethane Rubber







	Medium

	Durometer 60A	15	168	3	75	180	Not Rated	Dark Gray	Yes	25	1	8644K28	000000


	Durometer 60A	15	168	3	75	180	Not Rated	Dark Gray	Yes	100	4	8644K29	000000
	Durometer 60D	15	168	3	75	180	Not Rated	Dark Gray	Yes	25	1	4423N101	00000
	Durometer 60D	15	168	3	75	180	Not Rated	Dark Gray	Yes	100	4	4423N104	000000




			Hard

			Durometer 85A	15	168	3	75	180	Not Rated	Black	Yes	25	1	8644K13	00000


			Durometer 85A	15	168	3	75	180	Not Rated	Black	Yes	100	4	8644K15	000000

No-Residue Mold-Release Lubricants

Aerosol

Can

Also known as paintable mold-release lubricants, these lubricants don’t leave a residue, so you can paint or finish the molded part without the need to clean it. Apply them to molds before casting so you can easily remove cast parts and prevent sticking, stretching, and tearing.

Silicone Rubber Additive—Lubricants with silicone rubber have a small amount of silicone for lubricity, but still allow you to paint molded parts without cleaning first. Use these lubricants to release large, intricate, or difficult-to-release parts.

	Container			Temperature, ° F			Each		Package
	Net Weight, oz.	Type	Additive	Min.	Max.	For Use With		Each	Pkg. Qty.		Pkg.
Sprayon MR 309 Paintable Release Agent



		12	Aerosol Can	Silicone Rubber	-40	550	Plastic	1409K33	000000	12	1409K331	0000000

Mold-Release Lubricants

Spray

Bottle

Apply these lubricants to molds before casting so you can easily remove cast parts and prevent sticking, stretching, and tearing. They leave a residue, so they shouldn’t be used on parts that need to be painted.

Silicone Rubber Additive—Lubricants with silicone rubber can be used with rubber and plastic.

	Container			Temperature, ° F			Each		Package
	Size	Type	Additive	Min.	Max.	For Use With		Each	Pkg. Qty.		Pkg.
Mold-Release Lubricant



		16 fl. oz.	Spray Bottle	Silicone Rubber	35	500	Plastic, Rubber	2343K37	000000	12	2343K371	0000000


		1 gal.	Jug	Silicone Rubber	35	500	Plastic, Rubber	2343K41	00000	4	2343K411	000000

Foam-Forming Flexible 3D Printer Filaments

Create soft, stretchy parts that are lightweight and foam-like, letting air and gas pass through yet repelling water. These filaments are a TPE blend with a filler that dissolves in water, forming hollow spaces that make up to 45% of the part.

These filaments work with fused filament fabrication (FFF) 3D printers. If using a glass print surface, apply an adhesive to prevent the filament from detaching. The recommended print speed is 25 mm/s. Submerge your part in hot water for about 24 hours after printing to dissolve the filler and expose the pores.

For extra support when printing complex designs, use structural support 3D printer filaments. They dissolve in water at the same time as the filler in these filaments.

Maximum exposure temperature is the point at which a printed part will begin to deform. Above this temperature, your part will start to lose structural integrity.

Tensile Strength—Tensile strength is the best measure of a filament's overall strength. Similar to the stress applied on a rope during a game of tug-of-war, it's the amount of pulling force a material can handle before breaking. A higher rating means a stronger filament. A tensile strength of 5,000 psi and above is considered good; 12,000 psi and above is excellent.

								Spool
	Dia., mm	Printing Temp.	For Printer Bed Temp.	Tensile Strength, psi	Hardness	Max. Exposure Temp.	For Min. Nozzle Opening Dia., mm	Dia., mm	Dp., mm	Material	Wt., g		Each
TPE Blend—Flexible







				Opaque Beige

				1.75	220° to 250° C 428° to 482° F	50° to 70° C 122° to 158° F	150	Durometer 91A (Medium Soft)	49° C 120° F	0.4	200	55	Plastic	500	4661N11	000000


				2.85	220° to 250° C 428° to 482° F	50° to 70° C 122° to 158° F	150	Durometer 91A (Medium Soft)	49° C 120° F	0.4	200	55	Plastic	500	4661N12	00000