In this article we will look at the following glass lamination interlayer types in detail, compare them, and look at their suitability for use in glass balustrading:
- Polyvinyl Butyral (PVB)
- Ethylene Vinyl Acetate (EVA)
- SentryGlas Plus/ Sentry Glass Plus Ionoplast (SGP)
What is a lamination interlayer?
Laminated glass is a safety glass where two or more panes of glass are laminated together. Interlayers are used in this process to bond the two panes together, so in simplistic terms the “glue” between them.
1. Polyvinyl Butyral (PVB)
Polyvinyl butyral (PVB) is the most common interlayer used around the globe in laminated glass manufacture. Its optical clarity, flexibility, and ability to adhere to many surfaces and be compliant and cost-effective make it a primary interlayer for glass manufacturers.
PVB interlayer is adequate for most residential, education, leisure and commercial projects.
PVB is available with Acoustic PVB, Tinted PVB, Solar performance PVB, Coloured PVB and Structural PVB options.
It is not advisable to use common PVB interlayers where the laminate will have prolonged exposure to moisture or water (i.e., constantly immersed in water or in areas where water doesn’t run off or dry out regularly) as it can cause de-lamination over time.
2. Ethylene Vinyl Acetate (EVA)
Ethylene Vinyl Acetate (EVA) interlayers are an alternate interlayer for laminated glass. Although not as commonly used, EVA interlayers offer high moisture resistance. They can be used in external and internal glazed applications when the edges are exposed to higher moisture levels.
EVA also allows additional products such as switchable privacy glass to be used in the build-up of the interlayer.
EVA is available with clear, tinted or coloured options
3. SentryGlas Plus/ Sentry Glass Plus Ionoplast (SGP)
SentryGlas Plus (SGP) Ionoplast interlayers were initially developed for the hurricane glazing market by the company DuPont and was acquired by Kuraray at the end of 2014. In simple terms, it is a “stiffer or more ridged” interlayer than PVB, so it adds structural strength to the panel (as well as bonding the sheets together as PVB does).
Although SGP laminated glass does cost a lot more than PVB Laminated glass, SGP laminated glass has 5-times the tear strength and 100-times the rigidity of standard PVB. This means that in the improbable event of both panes of toughened glass breaking, the SGP will, in most situations, hold the glass in an upright position.
Made using Ionoplast polymer technology, SentryGlas® is chemically different from PVB (like Trosifol and Butacite), making it water-resistant, clearer and stronger. The advanced polymer used is also less likely to yellow over time.
However, as an Ionoplast interlayer, it is not compatible with other types of interlayers, so you cannot combine SGP with PVB/EVA based interlayers.
Creating a Sentry Laminated Glass panel is a very similar process to PVB lamination, but using a sentry laminate will usually allow the use of slimmer glass panels with less defection and greater strength.
As SGP is a thinner interlayer, the edge of the glass does look neater than other interlayers. It is still visible but not nearly as noticeable.
Due to limited colour availabilities, glass selections or ceramic print options may need to be factored in for specific design requirements.
All these interlayers are suitable to use in balustrades and the final selection will really be down to four criteria:
- Location of the installation
- Loadings required to meet the regulations applicable to your installation
- Your budget
- How the glass will be installed, different systems may require different interlayers to meet the required regulations.
Whilst SGB Laminated glass is more expensive than PVB or EVA laminations, some of the cost may be offset against other structural considerations such as using thinner glass overall etc.
Remember, there are different glass colour options to consider, read more in our separate article here.