Last update: 01.10.2020
Standards & norms

Material compatibility

As a building material, glass comes into direct or indirect contact with a number of other materials such as PVB films, insulating glass edge seal, setting blocks, press sealing of pressure glazing or sealing mass and elements at joint gaps and glass corners.

As a building material, glass comes into direct or indirect contact with a number of other materials such as PVB films, insulating glass edge seal, setting blocks, press sealing of pressure glazing or sealing mass and elements at joint gaps and glass corners. Preconditions should be checked as to whether the individual materials have any harmful interactions between them.

Decomposition of the butyl sealing by migration

Interactions are all physical, physical-chemical or chemical processes that, in the short, medium or long term, may lead to changes in the structure, colour or consistency. Even materials that are not in direct contact, but merely in the vicinity, can generate interactions through migration. Especially those products that contain softeners may, in the case of incompatibility, result in other adjacent materials absorbing these softeners as solvents and changing their consistency completely.

Setting block after harmful interactions

As the components used during the construction phase rarely come from the same producer, these compatibilities should be checked – by testing if necessary. Generally speaking, it is imperative to plan carefully and carry out work with the assistance of all participants and their product specifications. The more complex the installed glass systems, the more essential this requirement is in order to guarantee longevity and lasting functionality.
A broad range of tested products (including specifications of their mutual compatibility) is available.


Sealant compatibility of coated glass


Edge deletion is necessary to ensure that chemicals in certain sealants do not attack the silver layer in the coating. Extensive testing has shown that for some of the coating types, edge deletion is not necessary. Note: when a sealant is put behind an existing coating, a colour change may be visible.

Different sealant types use different mechanisms for sealant cure and some of the chemicals used in the curing process may attack the coating. For this reason, only approved sealants should be used.
The use of untested coated glass or unapproved sealants requires edge deletion in any case!

Important note:

  • Guardian SunGuard® SuperNeutral (SN), SuperNeutral HT (SN-HT) eXtraSelective (SNX) and eXtraSelective HT (SNX-HT): edge deletion required
  • SunGuard® Solar and High Durable (HD): no edge deletion required
  • SunGuard® High Performance (HP): no edge deletion required if applied sealants and related applications are tested and approved (list of compatible sealant types available at the Guardian Technical Advisory Centre)
Overlapping coatings

Where edge deletion is required, remove the coating by using grinding appliances and grinding wheels developed specifically for this purpose. More information ont the appropriate types may be directly requested from Guardian.
Any overlapping of coatings and sealants should be limited to a maximum width of 2 mm. The figure illustrates this requirement as an example in an insulated glass unit. The ground-off margin should generally not be wider than 10 mm, otherwise it may enter the visible area. If for any reason the sealing depth of the insulated glass has to be increased, then the width of edge deletion of the coating must be increased accordingly. A coating detector can be used to check whether all coating has been removed.

Important note:
Where the edge deleted part is visible from the outside of the building, a colour difference will be visible with the coated part of the glass. In the case of structural glazing, please contact the sealant manufacturer for further information. Guardian recommends a mock-up to secure the static requirements. For special applications such as step glazing with exposed coated surfaces (e.g. roofs, corners of structural glazing, etc.), please consult the local Technical Advisory Centre at Guardian.

Guardian SunGuard coatings in structural glazing


According to ETAG 002-1, multifunctional glass without approval from a notified body institute for monolithic applications (such as SunGuard HP, SunGuard SN and SunGuard SNX) or thermal insulating low-E glass (such as ClimaGuard) is not suitable for structural glazing. In this case, the coating needs to be removed accordingly.

Typically, applications with structural bonding need to be tested and approved. If a European certification for structural glazing according to ETAG 002-1 is required, please contact Guardian for detailed information on suitable glass types and tested coating-sealant combinations that comply with the ETAG 002-1 requirements.

For more information, please also consult the Product Application Information „Sealant Compatibility and Structural Glazing“ available at Guardian.


Ceramic printing on coated glass


Enamels have been carefully developed for printing and firing on normal soda-lime based float glass. During the tempering process of the glass, these enamels melt and fuse permanently to the glass surface to form a coloured ceramic layer.

Various Guardian SunGuard® coatings can be printed with ceramic paints (please contact the Guardian Technical Advisory Centre for a list of SunGuard coated glass that can be printed and the recommended enamel types).
Glass enamels may react during firing with coatings, causing some hazy appearance or even complete destruction of the coating. Therefore, it is necessary to test the compatibility of enamels with coated glass, under production firing conditions in order to achieve optimum results. It is recommended to run preliminary tests with the selected ceramic paint/glass combination, using the intended production furnace, glass geometries and ceramic covered areas. Unfavourable temper conditions could be the reason for poor results (low gloss, colour, homogeneity, durability, density, adhesion).

Compatibility and suitability tests are essential for each project. Any printing on a coated glass surface can create colour deviations after firing. Full size project mock-ups are advisable. The processor is responsible for quality control and quality of the final product.

SunGuard® products can be printed with ceramic paint for various purposes:

  • Decorative print
    • Patterns (dots or lines) which are applied to the coating by silk-screen printing.
    • Must be used facing inside the cavity of insulating glass only. →For more information see chapter Building with glass
  • Parapet wall glazings / spandrels (ceramic paint covering the whole coated surface)
    • With SunGuard® Solar and High Durable coatings only.
    • Can be used as a single glazing.
    • Ceramic paint needs to cover the SunGuard® coating in order to ensure effective protection from any environmental influences.→For more information see chapter Building with glass
  • Edge enameling
    • Covers up construction elements in the edge area.
    • Protects IG sealants against UV radiation.
    • No common approval in combination with SunGuard® HP. Please contact Guardian!
    • Edge enameling of SunGuard® HP with a width of more than 5 cm can be critical due to the different heating behaviour of the coated and uncoated surfaces.
    • Stepped insulating glass units with enameled SunGuard® HP on the outer pane are not permitted unless the enameled surface is additionally protected by suitable sealing material.
    • Another possibility for edge-enameling of coated glass is “Guardian System TEA”. Detailed information regarding compatible coatings and application methods are available at the Guardian Technical Advisory Centre.→ see also chapter Building with glass


Requirements on enamelling of SunGuard for monolithic spandrel applications

After performing extensive internal tests, Guardian recommends the following procedures:

  • All enamels must not contain the following ingredients: lead, cadmium, graphite, lithium, carbonate.
  • Minimum thickness of the wet coating after printing with correct adjusted processing viscosity:
    • 70 μm by silk-screen printing (e.g. silk-screen type PET 1500/32-100)
    • 90 μm by enameling with roller coating
  • Complete drying through the entire thickness of the enamel must be ensured before firing.
  • The final thickness of the enamel coating after firing should not be less than 30 μm.
  • The ceramic frit must melt without bubbling, under normal temper conditions for flat glass, in order to ensure a dense and uniform cover with a minimised porosity.
  • Minimum quality control of the final product:
    • All test methods recommended by the enamel manufacturer
    • Scratch resistance and adhesion (test with Erichsen-pen)
    • Porosity and adhesion (iso-propanol test)
    • Melting behaviour and surface roughness (gloss test with gloss meter)
    • Uniform and dense coverage 
    • Detection of pinholes in transmission – halogen lamp test: installation of a halogen lamp (min. 100 W) at a distance of max. 50 cm from the glass. Evaluation of the glass pane in transmission, viewing on the enameled side regarding number, dimension and distribution of the pinholes (selection of the worst area, not more than 30 pinholes / dm², single holes not larger than 0.2 mm in diameter). The distance of the observer to the glass should be not more than 50 cm.
  • The processor must follow specific processing instructions supplied by the enamel producer.

Ceramic print with Ferro System 140

Ferro and Guardian have tested “System 140” colours using recommended solvent “Medium 80 1022” or “Medium 80 1026” on selected Guardian SunGuard products from the following families (for detailed information please contact the Guardian Technical Advisory Centre):

  • SunGuard HP
  • SunGuard Solar
  • SunGuard HD

The Ferro System 140 includes various types of ceramic paints, composed of partially different chemical components. In relation to the glass products indicated above, Guardian recommends the following types:

  • Spandrel glass*:  
    • 140 12 4061 (colour similar to RAL 5007 Brilliant blue)
    • 140 12 4060 (colour similar to RAL 5014 Pigeon blue)
    • 140 11 4060 (colour similar to RAL 6000 Patina green)
    • 140 15 4001 (colour similar to RAL 7031 Blue grey)
    • Special colour adaptations from company Ceramic Colors Wolbring for colour matching solutions based on clear float glass (Wolbring colour numbers available from Guardian or in -> See Product Selector)
    • 140 14 4001 (colour similar to RAL 9005 Deep black) for printing on #4 in IGU solutions
  • Edge enameling:    
    • 140 14 4001 (colour similar to RAL 9005 Deep black)
    • 140 14 4011 (colour similar to RAL 9005 Intensive black - more pigments) 

* Increased energy absorption in IGU spandrels may result in both lites requiring heat treatment. The air gap should be limited, where possible, to 8 mm.

It must be ensured that monolithic SunGuard® spandrels are not exposed to any aggressive media before, during and after installation.

Spandrel recommendations for SunGuard architectural glass →See Product Selector


SunGuard HD in combination with ceramic print on surface #1

Special applications, such as ceramic frit on surface #1, may require the tempering of the glass with the coating facing down.

Such a particular application requires sufficient processing equipment. In particular, the ceramic rollers of the furnace must be clean of dirt and the glass should not be slid over stationary machine parts (rollers, castors, etc.).

Production set-up as well as a mock-up are mandatory. However, Guardian tekes no responsibility whatsoever and will not be held liable for any damages whatsoever such as, but not limited to, surface damages resulting from this type of processing.

Provided that the tempering is performed properly, the overall glass performance, such as light transmission or shading coefficient should not deteriorate.

For special applications, please consult the Guardian Technical Advisory Centre.


Architectural coatings in laminated glass


Guardian SunGuard® products can be produced as laminated glass for safety and sound control requirements. To maintain aesthetics and ensure superior performance, special care must be taken during the fabrication.

The coating can be applied on surface 4 (laminated with coating outside) or on surface 2 (laminated with coating against PVB).

Coatings SunGuard

If the glass is laminated with coating outside (surface 4) special attention must be paid if the coating is exposed to mechanical contact - especially if nip rolls are used for the pre-lamination process. The coated surface requires quality control after each fabrication step under suitable light conditions. 

Regarding any further handling (e.g. transportation, cutting, edge working, washing) specific instructions for handling of SunGuard products shall be followed. If you require more information, please contact Guardian.

If the glass is laminated with the coating against PVB (surface 2), SunGuard products are able to enhance the overall aesthetics and performance of laminated glass. However, thermal performance (SunGuard® HP and SN) may diminish. Guardian can assist its customers in estimating thermal performance based on the application. In addition, a colour shift may be noted when projects involve laminated and monolithic products side by side. Guardian recommends a mock-up.

Please contact the Guardian Technical Advisory Centre for information on coatings compatible with PVB interlayers.
Conditions that affect non-coated laminated glass can also have an adverse effect on coated laminated glass products.
Without compatibility tests, the direct contact between PVB and any sealant materials should be avoided. Generally, laminated glass must not be stood in water or be exposed to high moisture. In order to avoid delamination or corrosion of the SunGuard High Performance coating, the glazing must be designed accordingly, and the processor is responsible for the correct application. As for edge deletion, in case of any doubts, Guardian recommends suitable edge deletion of the SunGuard HP coating in order to avoid edge corrosion. SunGuard SN coatings must be edge deleted.

The following issues require special attention when using laminated glass with coating against PVB:

  • Slight colour shift compared to non-laminated glasses of the same type
  • Loss of thermal insulation performance of the coating (U-value)
  • Inside laminated coated glass products generally comply with EN 12543p3 laminated glass. Only a few inside laminated coated glass products comply with EN 12543p2 laminated safety glass. For further information, please contact your Guardian representative
  • In combination with selective coatings (e.g. SunGuard HP or SN) only one production run of the coated base glass should be used due to stronger requirements on colour tolerances (please contact Guardian regarding your particular project or further information)
  • For durability tests of laminated glass, please refer to EN 12543-4
  • To avoid punctual stress, special care must be taken as to the drill alignments

Guardian does not recommend use of resins, structural PVB, SentryGlas or EVA foil unless compatibility tests have been successfully performed. If these materials are intended to be used in direct contact with SunGuard, a suitable compatibility test performed by the processor is mandatory.