The versatile chemistry for electronic assemblies, filter applications and more...

FERMADUR® is the brand name for Sonderhoff Chemicals’ 2-component polyurethane systems for the production of hard to gel-like potting products.

They are directly applied to the part with the aid of mixing and dispensing systems with FIPFG sealing technology (Formed-In-Place Foam Gasket) and cure there.

Chemical constituents

FERMADUR® systems consist of a base resin (A-component) and a hardener (B-component) which are mixed together in a prescribed ratio. This produces a bubble-free potting within a few minutes.

Many technical applications in diverse industries require the protection of electronics or electrical components against environmental influences, electrical or mechanical interference and manipulation.

Sonderhoff has access to more than 500 FERMADUR® recipes, which fulfil the industry-required high seal impermeability standards, as well as those regarding stability and temperature, ageing and weather resistance.

Your product is important to us – we will be happy to advise you!

Physical and chemical Properties*
Appearance black or grey, other colours upon request (including transparent)
Hardness covering the entire Shore A range up to 80 Shore D also gel-like
Density from 0,8 g/cm³ to 1.7 g/cm³
Reacton time adjustable from 60 s to 180 min
Flame retardant flame retardant up to UL-94 V-0 possible, even with 2 mm coating thickness
Other properties
e.g. transparent, light-fast, with good thermal conductivity, can be used for rotation moulding,  dissipates static, hydrophobic, also available as a syntactic foam, with multilevel flow behaviour,  treated with microbicide, abrasion resistant, greater adhesion



Potting systems in difficult conditions

The FERMADUR® potting systems are, with their many different characteristics, also available for use in very difficult surroundings, from outdoor or underwater uses to flame-protected applications for lighting in tunnels, or from uses requiring ATEX protection in explosion risk zones right up to optical potting, with good heat dissipation qualities for the high temperatures produced by high-power LED light technologies.


Swimming pool lighting

Depending on the complete construction, part and potting can reach impermeability classes to IP68 with FERMADUR®, meaning that e.g. swimming pool lighting is possible.

Tunnel lighting

For tunnel lighting flame-retardant FERMADUR® products can be created to meet UL94 V-0 testing standards.

EX protected lighting

For explosion-protected lighting elements, e.g. for emergency lighting in hazardous surroundings underground, our FERMADUR® potting systems are formulated to withstand ATEX system testing in accordance with ATEX Directive 2016/34/EC.

Sealing of LEDs

The transparent polyurethane-based FERMADUR® potting products, e.g. for the sealing of LEDs, are protected from UV-radiation by the use of aliphatic isocyanates and are temperature-stable to 130°C.


Broad potting spectrum covers very different requirements


The function of the FERMADUR® potting system is determined by its application and can range from part protection against environmental influences through the sealing of electrical assemblies to the gluing of components such as the filter systems used in industry and the home.

Component sealing with FERMADUR® potting protects parts from infiltration of damp, dust, foreign bodies, water and so on. The chemical properties of the material recipe can be varied so that the potting mass can be perfectly adapted to the task placed on it.

FERMADUR® potting also can be used to join electronics together and for interference protection and electrical insulation of cables and plugs. Potting increases the mechanical stability and dielectric strength of the electronic parts, their vibration and shock resistance.

Potting with FERMADUR® products impedes detachments or the opening of crevices at the edge of the potting mass because of dramatic temperature differences or vibrations, so that damp or aggressive materials cannot penetrate the part and adversely affect its functionality or even destroy it.

According to their conditions of use, FERMADUR® potting systems can be adapted widely for their ease of flow, reactivity, hardness grade and colour.

FERMADUR® potting possesses a very high tear resistance and flexural strength, so that components can still be used under extreme environmental conditions.

FERMADUR® – The great application diversity

The FERMADUR® potting systems offer a wide range of properties for different applications and requirements, from potting for lighting and sensitive electronic components, through the bonding of filter packets and viewing windows in control cabinets to the coating of conveyor belts and transparent component surfaces.

Applications* Viscosity (A)
Shore 00
Other properties*
A-610 Potting compound for sensitive electronic components, circuit boards and sensors ca. 2.000 gel-like
- A40
1,20 Consistency adjustable across the range of mixing ratios, soft and tear resistant
A-113 Potting compound for instrument and connector plugs ca. 1.000 A45-A55 1,15 Flexible, levels very well, low shrinkage, low surface tension
A-606 Special potting compound for electronic components ca. 1.200 A45-A60 1,20 Flexible, mechanically particularly stable, tensile strength approx. 7 Mpa, elongation at break approx. 350%
A-134 Potting compound for sensors, circuit boards, electric switches and sensor elements ca. 1.800 A60-A75 1,35 Flexible standard systems for electronics in the automotive industry, listed in various OEMs, good adhesion
A-125 Potting compound for plugs ca. 1.500 A60-A75 1,20 Flexible potting compound, low shrinkage, low surface tension
A-203 Potting compound for transistors ca. 1.200 A60-A80 1,20 Flexible, for sensitive electronic applications, low shrinkage, low surface tension
A-680 UL2 Potting compound for sensors and circuit boards ca. 7.000 A60-A80 1,60 Conforms to UL94 V-0 listing at 2 mm, elastic
A-680 UL1 UL94 listed potting compound for transducers ca. 6.000 D80-D85 1,60 UL94 V-0 listing at 1.5 mm, hard, good thermal conductivity
A-117 Potting compound for transformers, voltage
transformers, capacitors, control units
ca. 23.000 D60-D90 1,70 Hard, thermal conductivity 0.9 W/mK, conforms to UL94 V-0 at 3 mm
A-111 Potting compound for sensors or circuit boards ca. 300 gel-like
- A60
1,25 Transparent, UV stable, tough-hard, temperature stable up to 165°C, high chemical resistance
A-180 Potting compound for light diodes ca. 500 A60-A80 1,25 transparent, UV-stabil, zäh-hart, temperaturstabil bis 165 °C, hohe Chemikalienresistenz
A-173 Potting compound for cable sheathing or moulded parts for cable routing ca. 1.000 A50 0,80 Slightly foaming, flexible, high longitudinal water tightness achievable
A-120 Adhesive for panes in enclosures ca. 200.000 D25-D40 1,30 Tough-hard, good adherence on various substrates, high mechanical stability, can be used as a glue, highly thixotropic
A-187 Rotation moulding compound for ferrules ca. 120.000 D50-D65 0,70 Hard lightweight potting compound, syntactic foam with low density, non-drip
A-172-2-CON Rotation moulding compound for ferrules ca. 250.000 D80 1,40 Non-drip, high stability and chemical resistances, static dissipative potting compound
A-640 Coating for conveyor belts ca. 23.000 A70-A80 1,25 Flexible, particularly tear resistant
A-196-4F Potting compound for filter end caps and adhesive for filter cartridges ca. 1.200 D30-D40 1,20 Microbicide, tough-hard, good adherence to various substrates, two-step flow behaviour available

* The description of the possible fields of use of our products as well as the technical data and values only have a general character and do not mean that a certain product can be used under all conditions in the respective field of use. In this respect, the stated field of use is not a binding specification or usage provision. Due to the great number of environment variables and their influences (e.g. temperature, test specimens, size, interaction with substrates, influence of machines, or the like) you as our customer must check whether the product is suitable for your specific field of use. We will be pleased to assist and advise you in this respect.


Good reasons for using FERMADUR®


  • FERMADUR® systems are the most suitable for sealing industrial components
  • After curing, FERMADUR® systems develop a crosslinked structure which is extremely resistant to environmental effects, such as humidity, dust, temperature and mechanical impacts
  • FERMADUR® systems react at room temperature in 1 – 180 min and although a furnance can reduce the reaction time considerably, it is not a necessity
  • FERMADUR® systems achieve particularly good adhesion to parts due to the chemical reaction of the two components on the carrier material
  • FERMADUR® systems offer exceptional long-term behaviour and are distinguished by high heat resistance and an extremely low expansion coefficient
  • The viscosity of FERMADUR® systems can be regulated from a thin fluid to a thick paste
  • FERMADUR® systems are also available in transparent and light-fast formulations
  • FERMADUR® systems have low shrinkage and low surface tension, very good dielectric properties and also very high impact strength
  • Processing machines for FERMADUR® systems can be adapted flexibly and quickly to other components at any time
  • By using FERMADUR® systems even small product series become profitable