Opti-tec 4210 Optically Clear, Hard Polyurethane Encapsulant and Potting Compound


Opti-tec 4210 is a two-part, high hardness, room temperature curing polyurethane resin designed for the potting and encapsulation of electronic devices requiring very high clarity. Opti-tec 4210 has excellent outdoor weathering properties, due to the incorporation of both UV resistant base materials and the addition of UV stabilisers and antioxidants. Opti-tec 4210 is a harder version of Opti-tec 4200.

Features & Benefits

  • Water clear – for high clarity potting, encapsulating, casting
  • Very hard, Shore D80 – resists scratching and marking
  • Excellent long term UV stability – can be used outdoors
  • Low viscosity – easy to mix and process
  • High mechanical strength


  1. Potting of LED lighting projects, including LED tracks, arrays, luminaires
  2. Protection of electronics located outside or walked on; uplighters
  3. Optical instruments
  4. High quality casting resin
  5. Lens forming
Opti-tec 4210 can be used to encapsulate LED uplights
Opti-tec 4210 can be used to encapsulate LED uplights


Resin Hardener Mixed
Colour Clear Clear Clear
Specific gravity (g/ml) 1.05 1.13 1.09
Viscosity m.Pa.s @ 25°C 2500 1200 1700
Mix ratio by weight 0.93:1
Mix ratio by volume 1:1
Curing (typical values – will vary according to mass and application. Higher cure temperatures will result in greater cure shrinkage and exotherm)
Pot life (100g mix @ 20-25°C) 30 minutes
Gel time (100g mix @ 20-25°C) 40 minutes
Light handling 48 hours @ 20-25°C
24 hours @ 40°C
12 hours @ 60°C
Full cure 72 hours @ 20-25°C
24 hours @ 40°C
12 hours @ 60°C
Cured properties
Water absorption 0.87% (30 days @ 25°C)
Shore D hardness 80
Operating temperature (application & geometry dependant) -55 to +120°C
Thermal conductivity 0.25 W/mK
Tensile strength 26 mPa
Elongation at break 5-10%
Compressive yield strength 30 mPa
Coefficient of linear expansion 60-80 pp/m°C
Volume resistivity 3 x 1014 ohm.cm
Surface resistivity 3 x 1015 ohm
Electric strength 20 kV/mm
Refractive index 1.47-1.48
Opti-tec 4210 is RoHS compliant and contains 0% REACH SVHC. Mercury free.

Ordering Information

Opti-tec 4210 is available in bulk, cartridges and twin packs.

Part number Description
OPT4210-50G Clear Hard Polyurethane Encapsulant – 50g double syringe cartridge
IDM805001 Syringe Gun – for 50g cartridges
OPT4210-250G Clear Hard Polyurethane Encapsulant – 250g twin pack sachet
OPT4210-1KG Clear Hard Polyurethane Encapsulant – 1 kilogram kit

For optimal results, store in conditions that aren’t humid and aren’t affected by direct sunlight. Store away from strong bases, strong acids, strong oxidising agents, water, amines and alcohols. Keep in the original packaging and store in a cool, well-ventilated area. Keep container tightly closed.

  • Last updated: July 2019
  • Version: 2.1

Statements, technical information and recommendations contained herein are based on tests we believe to be reliable but they are not to be construed in any manner as warrantees expressed or implied. The user shall determine the suitability of the product for his intended use and the user assumes all risk and liability whatsoever in connection therewith.