Technology of Glazing under Pressure

Acrylic vs. Polycarbonate: a Quantitative and Qualitative Comparison

Acrylic often compared to Polycarbonate, which is an other transparent plastic, that is sometimes used for bearing loads. Polycarbonate is sometimes called Lexan®, which is a trademark by GE Plastics. An other popular brand name for Polycarbonate is Makrolon®, owned by Bayer. Acrylic on the other hand is often called Plexiglas. Plexiglas ® is a… Read more »

Why not to use Glass for Underwater Windows

The picture shows the two best reasons why not to use float glass for underwater windows: The window is supposed to be transparent. Instead it is green like a water bottle. Note that float glazing needs to be very thick to withstand the water pressure. The transparency of float glas is lower than that of… Read more »

A comparision of waterproofing slurries

Waterproofing slurries are used to make floors and walls resistant against water. They are used for many applications where water resistance of building components is important. We compare only those slurries, which are suitable for standing seepage water and water under pressure. A water level of several meters on top of the waterproofed surface should… Read more »

Technical Information on Acrylic

Acrylic Panels – more translucent than glass and a great insulator – are used as an alternative to traditional float glass. When it comes to withstanding pressure acrylic panels are superior as they are less brittle and hold back higher loads. That is why it is the material of choice for underwater viewing. Acrylic Panels have the… Read more »

Plexiglas Acrylic made by Röhm

Roehm (also spelled Röhm) invented acrylic glass / Plexiglas® 1933 and was a major player in acrylic appliances ever since. Röhm’s Specialty Glazing division has its main production line near Darmstadt, Germany. In 1999 Degussa acquired Röhm GmbH. In 2006 Degussa was then purchased by Evonik, which resulted in the new name Evonik Degussa Gmbh. Plexiglas®… Read more »

Optical Performance Requirements for Acrylic Windows

The optical transmission properties of acrylic glass is excellent. It’s value is about 92 compared to 90 of float glass. [1] The air or “dry” side optical performance demanded of the windows in an aquarium is similar to that of picture windows in stores or residences (except that minor wet side distortions are corrected by… Read more »

Cleaning Acrylic Windows

Dirt cannot cling to the smooth surfaces of acrylic. But, plastics might become statically charged and, as a result, attract dust. Out of doors this is usually prevented by air and moisture, whereas in closed rooms this phenomenon is promoted by mechanical friction at the plastics’ surfaces, air currents and dry air. Dust is removed… Read more »

Glass vs. Acrylic: a Comparision

Plexiglas is often chosen as an replacement material to mineral glass (also called flat glass, Borosilicate glass or Echtglas in German). Plexiglas© (which is a brand name for acrylic) and mineral glass are both transparent building materials. Differences in the properties of the two materials include: Acrylic glass transmits more light than glass. Up to 92% of visible light is… Read more »

Fire Rating of Acrylic

Both cast and extruded Acrylic burn more or less like hardwood; very little smoke generation. Its combustion gases are non-toxic and non-corrosive. Cast PMMA (Acrylic) is classed Classification E, according to the “EURO-Norm” (DIN EN SO 11925:2:2002-07) . Find the test report  here (German only). B2, with no burning droplets, according to DIN 4102 (Germany)… Read more »

Acrylic Panel Thickness

Acrylic windows under hydrostatic pressure, e.g. aquarium panels, have to retain the massive water load of the water column in the tanks. In public and private tanks the safety of the viewer but also of the marine life should be considered as vital. The design engineer therefore has to limit the material’s tension and the… Read more »

Acrylic and Ultraviolet Light

Unlike glass, acrylic glass does not filter ultraviolet (UV) light. Acrylic glass transmits UV light down to 300 nm. Hydrosight acrylic includes an additive to make the acrylic absorb UV light. This property is wanted for most applications, e.g. aquariums and architecture. However we can deliver specialized acrylic, that allows UV transmission. This might be… Read more »

Waterproofing Swimming Pools

The walls and the ground of a swimming pool are subject to constant water pressure. For enjoying the swimming pool it is important to have a permanent waterproofing. For waterproof structures made of concrete we have in the German language two expressions that have no real equivalent in English: The “Weisse Wanne” (white tub) and… Read more »

Thermoforming Acrylic Panels

“Many of the spherical sector windows in service today have been thermoformed and their service record is outstanding.” Jerry D. Stachiw Thermoforming is a process of 2 or 3 dimensional forming of acrylic material. It is the recommended alternative to casting 3 dimensional objects in its finished shape in molds from slurry. Casting acrylic is a… Read more »

Structural Acrylic

Acrylic is a very unusual material. It serves not only optical but also structural purposes. Its optical properties are well understood and are used in diverse optical applications. Because of its transparency, it is also utilized in applications where it must resist static and dynamic forces, for example, as windows or shells of pressure vessels under external or… Read more »

Shapes of Aquarium Tunnels

Cylindrical Aquarium Tunnel Tunnels are typically cylindrical in design. The most common tunnel has a constant radius and spans 180°. These tunnels can be faceted to make turns within the tank. The ideal tunnel has the viewer at some point completely surrounded by water so that in whatever direction they look, they only see water. A… Read more »

Polishing Acrylic & Optical Distortions

Acrylic Windows with a damaged surface do not necessarily need to be replaced like float glass – they can be repaired. For instance aquarium windows, that are exposed to the public for several years, might show scuffs due to vandalism. Improper cleaning by inexperienced personnel could lead to blemishes. Hydrosight can organize related service work such… Read more »