Six base elastomers, over 800 custom formulations mixed and tested in-house. Choosing the right polymer is the single biggest factor in a long-lasting, failure-proof component. This page tells you how we choose.
Tell us the conditions your part will face. We narrow six polymers down to the one that survives them, with a spec you can send us in a tap.
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2 · What does it touch? pick as many as apply
3 · Any special demands?
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Our pick
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No obligation. We reply with price and lead time.
Service Temperature
Temperature range for each polymer
Every bar grows out from ambient. Cold side left, heat side right.
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-70°C20°C ambient+140°C+250°C
The Sunlight Test
Ten years outdoors, in ten seconds
UV and ozone attack the polymer backbone, not just the surface. Crazing becomes cracks. Cracks become failure. Watch which elastomers hold.
Side by Side
Full Property Chart
Property
NBR (Nitrile)
CR (Neoprene)
EPDM
Silicone (VMQ)
FKM (Viton®)
SBR
Hardness (°Shore A)
30-95
35-95
35-85
20-90
55-90
40-90
Temperature Range (°C)
-40 to 110
-40 to 110
-50 to 130
-60 to 225
-30 to 230
-40 to 90
Electrical Resistance
Poor
Good
Good
Best
Good
Fair
Abrasion Resistance
Excellent
Poor
Good
Fair
Excellent
Excellent
Oil / Acid / Petrol Resistance
Excellent
Fair
Poor (Good with acids)
Oils Poor, Acids Good
Excellent
Poor
Weather & Ozone Resistance
Very Poor
Good
Very Good
Best
Good
Poor
Steam Resistance
Poor
Fair
Best
Good to 121°C
Limited (special grades good)
Poor
Viton® is a registered trademark. Figures are indicative. Tell us your operating conditions and we'll recommend the right polymer.
Silicone
VMQ / Silicone Rubber
Our speciality, from very soft 30 Shore A extrusions to silicone sponge. Grades built to FDA 21 CFR 177.2600, BfR XV and USP Class VI (ch 87 and 88) for food, beverage and pharma service.
Engineer's note
Brilliant across temperature, from deep cold to real heat, and clean enough for food and medical. Compression set is excellent, so seals stay springy and keep sealing for years. Two honest cautions: it tears and abrades more easily than most, and it is very hard to bond or glue. If physical strength is also a requirement, let us know. Special grades can handle it.
LED LuminairesFood & Pharma TubingMedical HousingsElectronics EnclosuresOven & Autoclave Seals
Continuous Service-60°C to +225°C
Short-Term Peak+300°C short-term (special grade)
Compression SetExcellent
ASTM D2000M2GE
Relative Cost●●●●○
Recommended for
UV & ozoneHot airWaterSteam to 121°CFungus
Keep away from
FuelsMineral oilsSuperheated steamSolvents
EPDM
Ethylene Propylene Diene Monomer
Handles steam and hot water better than most elastomers, resists temperature cycling, and does it at a very competitive cost. The default choice for outdoor enclosure seals, pipe gaskets and potable water applications.
Engineer's note
Nothing beats it outdoors. Sun, ozone, rain, years of it, and EPDM shrugs it all off. Just keep it away from oil and fuel. That is the one thing it cannot take.
Outdoor EnclosuresPipe Joint GasketsPotable Water (BS 6920)Solar & Street LightingAutomotive Weatherstrip
Continuous Service-50°C to +130°C
Short-Term Peak+150°C short-term
Compression SetGood
ASTM D20002CA
Relative Cost●●○○○
Recommended for
SunlightOzoneSteamHot waterWeak acids
Keep away from
Mineral oilsFuelsSolventsGrease
FKM
Fluoroelastomer (Viton®)
The premium polymer for aggressive environments: fuels, mineral oils, hydraulic fluids, acids and continuous high heat. Where NBR gives up, FKM keeps sealing. Not for ketones, esters or amines, and standard grades dislike steam. FDA and USP Class VI compliant FKM grades are available for food and pharma duty.
Engineer's note
Heat, no problem. Oil, no problem. Fuel, no problem. The one catch: if your fuel has ethanol in it, standard Viton swells. Ask for the flex-fuel terpolymer grade (E20, E50, E85) and you're covered.
Petrol & dieselMineral oilsMost acidsOzone & UVHigh heat
Keep away from
KetonesEstersAminesBrake fluidSteam (std. grade)
NBR
Nitrile Butadiene Rubber
The industry standard for oil and fuel contact at moderate temperatures, with excellent abrasion resistance and a wide hardness range. Proven across automotive, hydraulic and general engineering duty. NBR is specified by acrylonitrile (ACN) content: high-nitrile grades (around 45% ACN) give maximum oil and fuel resistance, while low-nitrile grades (around 18 to 20% ACN) trade some oil resistance for better low-temperature flexibility.
Engineer's note
The oil-and-fuel workhorse, and the value pick. It just does not like sunlight or ozone. If the part lives outdoors, go Neoprene or EPDM instead. Indoors around oil, nothing gives you more for the money.
Mineral oilsPetrol & dieselGreaseHydraulic fluidWater
Keep away from
OzoneSunlightKetonesBrake fluid
CR
Neoprene / Chloroprene
Inherently flame retardant, which makes it a frequent pick for electrical and marine duty.
Engineer's note
The all-rounder. Takes weather, moderate oil and a bit of flame without complaint. It rarely wins any single category outright, but when a part sees a little of everything, this is the safe call.
Good impact strength and aging behaviour, ideal where volumes are large and the environment is mild.
Engineer's note
Cheap, tough and great against abrasion, which is exactly why it belongs indoors and dry. No oil, no ozone, no sunlight. For general-purpose pads, bushes and buffers on a budget, it is hard to beat.
WashersPads & BumpersGeneral MouldingsWater ServiceHigh-Volume Parts
Continuous Service-40°C to +90°C
Short-Term Peak+100°C short-term
Compression SetFair
ASTM D2000AA
Relative Cost●○○○○
Recommended for
AbrasionImpactWaterMild chemicals
Keep away from
OilsFuelsOzoneSunlightHeat
Not sure which polymer?
Tell us the application. We answer with a grade, a price and a lead time.