Nonwoven glass mat facers are widely used in the gypsum sector to provide a number of additional benefits to wallboards. Global Gypsum recently spoke to Johns Manville about the use of nonwoven glass mat facers in what the company calls this ‘key strategic sector.’
Global Gypsum (GG): Please could you introduce the company Johns Manville (JM)?
Souvik Nandi, Global Innovation and Commercialisation Leader for Glass Mats (SN): JM is a global manufacturer of premium building products that is owned by Berkshire Hathaway. Based in the US, the company began as a roofing company in 1858 in the basement of a New York City apartment. The company, started by Henry Ward Johns, later merged with a company owned by Charles B. Manville, who was manufacturing a complementary portfolio of products.
In 1972, Johns Manville moved its headquarters from New York City to Denver, Colorado. It developed a research centre in nearby Littleton. In 2001, the company was acquired by Berkshire Hathaway. Over the years, the company has grown via acquisitions in North America and Europe. Our plants are located in the US, Canada, Germany, Slovakia and China. Today Johns Manville is a prominent producer of fibres for inside wallboards and Evalith® glass mats for use on the exterior of wallboards.
GG: Could you please introduce JM’s glass mat facer activities?
SN: JM has provided glass mats for gypsum wallboard producers for around 20 years. Over the years this has developed into a range of products that can be split into two broad categories: coated and uncoated. Coated facers were most commonly used historically. However, JM was the first to develop uncoated glass mat facers for the sector.
GG: Where does JM make such products?
SN: We produce our glass mat products at our Waterville (Ohio) facility and at our Wertheim site in Germany. Both locations produce glass mats for gypsum and a wide variety of other sectors, as well as the fibres used to produce the glass mats. The fibres are also used in a wide range of sectors.
Both sites are very well established JM facilities. Waterville has been operated by the company since the 1940s. The Wertheim site was originally operated by Schuller, which developed the wet-laid glass mat production process that JM uses today. JM actually bought a license for the process from Schuller first and then bought Schuller itself in 1971.
GG: What breadth of products can be made?
SN: There are a lot of options and we can customise a product around each client’s needs. What works for Customer A’s process might not work for Customer B’s process. This is because all wallboard processes are slightly different. On top of that different producers might be looking to achieve different end results from using glass mat facers. We have a range of tools in our tool box.
GG: What are the main tools you can use?
SN: There are two main ones: fibres and binders. As we produce our own fibres, we have access to a wide range of lengths, widths and sizings. We also have a variety of binders that provide different beneficial properties to the gypsum wallboard.
GG: What advantages are there to using glass mat facers?
SN: Glass mat facers can be tuned using different binders and other additives to offer fire-resistance, moisture-resistance and protection against the effects of weather, including additives that protect against UV radiation. The glass also provides mould and mildew resistance.
This means that wallboards that incorporate glass mat facers are suitable for use in external environments, in which paper-faced boards would rapidly fail, including as the final layer that is directly exposed to the elements. This opens up new markets and applications into which wallboard producers can expand. This includes building interiors too, for example for schools and hospitals.
GG: Do glass mat facers help with mechanical strength in any way?
SN: Glass mat facers don’t provide load-bearing characteristics but do offer protection against crack propagation. The glass slows down or stops the propagation, like a sticking plaster on the outside of the gypsum plaster! The glass also provides additional strength against snapping during installation.
GG: Does the glass provide noticeable extra weight?
SN: The weight from the gypsum far outweighs the weight of the glass so installers don’t notice the difference.
GG: Are you aware of any disadvantages from the inclusion of glass mat facers, for either wallboard producers or installers?
SN: We are not aware of any particular request or area for improvement that has been presented to us by either of those kinds of stakeholders.
GG: Please can you outline the production of glass mat facers?
SN: We take our internally-produced fibres and put them into water to form a slurry. This is poured onto a lay-belt, which is perforated, ensuring that the fibres are distributed randomly into a sheet as the water drains away. The sheet of fibres passes onto a second belt where the binder is applied. The binder can be either organic or inorganic in nature or a combination of the two.
The wet nonwoven is then fed into our oven, which dries and cures it. This produces our uncoated glass mat facers. It is important for the temperature distribution to be even in each zone of the dryer to get the correct drying time, curing time and surface characteristics. We want a smooth surface that is uniform, with very little variation in density and thickness.
We also have the ability to apply a highly filled mineral coating on our glass fibre nonwovens.
After they are cured and dried, the facers are collected on large reels and distributed to our gypsum wallboard clients, as well as a wide range of
other users.
It is important to remember that these lines are not dedicated to gypsum mat production. The products made using them are used by JM to supply a very wide range of applications, including roofing, flooring, ceiling tiles, insulation facers, battery separators and a range of players in the composites industry. Glass mat production is JM’s most diverse sector in terms of industries supplied.
GG: What is the residence time of a fibre from entering the line to being cured in a sheet?
SN: The time is actually quite short for both processes. From the slurry to the oven is in the order of dozens to hundreds of seconds. It is slower than a wallboard paper line but faster than something like a mineral wool process. The largest piece of equipment by far is the dryer.
GG: How does the wallboard producer use JM’s product?
SN: They put it on the unwind station and use it in the process, exactly as if it was a reel of paper.
GG: Do different types of gypsum (natural, synthetic, recycled) require different types of glass mat facers?
SN: There are, of course, some differences between natural and synthetic gypsum. However, this does not really affect the specification of the glass mat facer that we provide. In a lot of cases in North America or Europe, the wallboard plant uses a mixture of gypsum sources or, if not, is able to use a mixture of types of gypsum. In these cases we provide a glass mat facer that is able to handle the variation in properties, i.e. specify to the type of gypsum that is most demanding on the glass mat facer.
GG: What makes JM’s glass mat facer products stand out from its competitors?
SN: Traditionally glass nonwovens are based on formaldehyde-based binders. However, JM has developed a range of other binders with low and ultra low levels of formaldehyde. This enhances the indoor air quality and meets the California 1350 standard, which states that formaldehyde concentration should be lower than 9μg/m3.
This means that wallboard producers can also meet this requirement and provide better indoor air quality in buildings such as schools and hospitals. Producers can then earn Greenguard or Greenguard Gold certification for their glass mat faced gypsum wallboard products.
We introduced the low formaldehyde-containing binder system in 2009 and the ultra-low formaldehyde-containing binder system in 2016. It contains around 5 - 7 times less formaldehyde than a glass mat facer made with a traditional urea-formaldehyde binder.
JM was the first and remains so far the only producer of glass mat facers for gypsum wallboard that contain such low levels of formaldehyde. We still retain some higher formaldehyde products too, to offer a full range to our customers.
GG: Are you seeing changes in what wallboard producers request with time?
SN: We are seeing more requests for lower formaldehyde emitting products. This is actually what led to the development of the ultra-low formaldehyde binder systems mentioned above.
GG: Do you have any comments on the recyclability of gypsum wallboard with glass mat facers? Some parties suggest this may be problematic.
SN: We believe that the recycling of the gypsum within such panels is not prohibited by the inclusion of a glass mat facer. You can keep the glass mat as part of the recycling process and include that as a glass fibre reinforcement inside the board.
GG: Where are the biggest markets for JM’s glass mat facers right now?
TJ Stock, Portfolio Manager, Glass Mat North America (TJS): The dominant market today is the United States due to the increasing acceptance to use gypsum exterior sheathing in construction, particularly commercial buildings and light industry.
We work with all of the US-based producers. Some have a larger market share position in external gypsum than others. Exterior sheathing is really driving demand for this, with interior applications still dominated by paper-faced gypsum wallboard. We estimate that less than 25% of wallboard is glass faced in the US currently. Of course, the next growth opportunity for glass faced gypsum could be the interior side. There are clear advantages in rooms like the bathroom, kitchens and anywhere else that is exposed to a lot of moisture.
GG: Where is the most important growing market?
TJS: At the moment a fast growing region is Europe. We have seen a lot of pick-up in this type of product in Turkey in particular, driven by a move to light-weight construction. We can only speculate as to what are the most important drivers but there are speed and cost advantages of taking this approach to construction.
GG: Souvik, TJ, thank you for your time today!
SN/TJS: You are very welcome!
