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We began by offering the 1st Hopper-Fed Hot Melt Extruders

Components Required to Make a Sealed Unit

An insulated glass (IG) sealed unit is made with two panes of glass (although triple glazing and even quadruple glazing with three or four panes of glass are also available) which are separated with a spacer frame made from tube or foam spacer (tube can be bent or cut and corner keyed). The spacer frame is fixed onto the two panes of glass with a primary sealant. A spacer tube is filled with desiccant on two to four sides of the frame (foam spacer is manufactured with a desiccant compound included) and then a secondary sealant is applied to the back of the spacer to seal the unit. Insulated glass sealed units can also be gas filled to improve their thermal efficiency.

Spacer Bar

Used to create the airspace between the two panes of glass and hold the molecular sieve (desiccant), spacer tube also helps to maintain a unit's structural integrity. It is available in a range of widths and lengths.

Small perforated lines run down the centre of spacer bar around its inner surface. Breather holes allow the passage of gas into the spacer bar where desiccant is held.

Alternatively, foam spacer can be used which is pre-desiccated and requires no corner keys or connectors.

Several types of spacer bar are available including: Aluminium , Warm Edge and Steel profiles in many colours. Warm edge bar offers a more thermally efficient solution. Those supplied by Thermoseal Group include: Thermobar (spacer tube) and Thermoflex (foam spacer) highest performance spacer systems.

Thermobar and Thermoflex are Passive House approved components for Arctic Climate Zones and all other climate regions with lower requirements. Thermobar is certified with a phA rating (phA+ with Hot Melt) and Thermoflex is certified phA+. These spacers also achieve best thermal values as certified by Bundesverband Flachglas Association.

For more information on the advantages of Thermobar warm edge spacer visit

For more information on the advantages of Thermoflex warm edge spacer visit

Corner Keys

Spacer bar can be bent or joined at the corners. Connectors and corner keys come in a range of sizes and colours which are compatible with specific profiles of spacer bar. Gas fittings are also available.


Inside the spacer bar, thousands of beads of desiccant are held. The sole function of the desiccant or molecular sieve is to adsorb any moisture in the airspace and keep the moisture from condensing on the inside surfaces of the glass. A high quality pure 3A desiccant such as Eurosiv is the best solution within a sealed unit as it selectively adsorbs moisture vapour and not other inert gases used in the construction of sealed units. Thermoflex warm edge foam spacer contains a 3A desiccant compound.

Primary Sealants

A dual sealing system makes up for over 90% of the European insulated glass market. The primary seal serves as an assembly support during the construction of the sealed unit. Once completed, low moisture vapour transmission rate and low gas permeability help stop the movement of water vapour and inert gases in and out of the sealed unit. Primary sealant is available in several block sizes and is compatible with butyl, PU, PS and Silicone systems. Thermoseal Group supplies a range of PIB including its own brand Euroseal PIB, and a range of PIB machines suitable for small and large IG manufacturers.

Secondary Sealants

An edge sealant bonds to the spacer bar and the glass to seal the edge of the unit to prevent moisture ingress. It also provides protection from gases passing into and out of its internal unit construction. Options include: Hotmelt, Polyurethane, Polysulfide and Silicone. This is critical to the integrity of the sealed unit. Thermoseal Group supplies a range of options for secondary sealant including its own brand Euroseal as well as other internationally-recognised brand sealants.

Gas Filling

Sealed units are often filled with an inert gas such as Argon, Krypton or Xenon. Gas-filled units are more thermally efficient and are often referred to as 'high performance' (providing the unit is constructed with an emphasis on preserving the gas within it).

The requirement to pass EN1279 part 3 standard and the pressure to gain a C+ Window Energy Rating (WER) is creating an increasing demand for units that are gas-filled.

Grille and Georgian Style Window Components

Adding Georgian grille and bar to the internal and/or external construction of a sealed window unit is a simple way to replicate classic old Georgian style windows. Georgian bar is stapled to or secured by drilled fittings to the spacer frame of the sealed unit and it is then sealed between two pieces of glass to create a Georgian design.

The types of Georgian systems include: Standard Georgian Bar; Surface Mount Georgian bar; Interbar; Victorian Grille, System 2 and Woodgrain Georgian bar.

Lead and Decorative Glass

There is a variety of other options available to decorate your glass and give your windows a unique design including: lead strip (available in a range of colours), coloured films, coloured resins and a multitude of decorative glass bevels which are bonded using special UV adhesives.

Would you like to know more?

Thermoseal Group

Our business is dedicated to the manufacture and supply of highest performance components and machinery used in the manufacture of insulated glass. Our particular focus Is on the development of components designed to help meet the changing requirements for more thermally efficient windows. We are a multiple award-winning organisation with almost 40 years in the industry.

Latest News

Thermoseal Group nominated as G23 'Component Supplier of the Year' Finalist
Date Added 03/10/23

Thermoseal Group is a finalist in the Component Supplier of the Year category in the G23 Awards, in recognition of its investment in infrastructure,... > More


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