Plastic glazing materials

Q. What is 'Plastic Glass'?

This description covers a wide range of materials. There are two main plastics used in picture-framing:

Styrene (extruded polystyrene sheets) and Acrylic (PMMA - extruded and cast). Styrene is used for all basic low cost purposes and Acrylic for more critical work. One other common plastic material is Polycarbonate - used mainly for high security applications as it is virtually unbreakable. It is not usually used in framing as it is costly and degrades over time due to the action of UV light.

Thicknesses used in picture framing run from 1.25-3mm and more. Stock sheet sizes run from 1220 x 914mm to 2000 x 1500mm and more.

Q. Are Plastics Really Shatter-proof or Unbreakable?

No - of course not! They do all have high resistance to breakage and in practice will usually survive impacts etc. better than the rest of the frame and much better than glass.

Q. Where Should I Advise Customers to Use Plastic?

The main benefits of plastic are: light weight, high breakage resistance and, when they do break, they don't pose much risk of injury. They usually cost a bit more than equivalent glasses. Main uses for plastic are therefore in high risk environments (schools, hospitals, offices, restaurants, etc.) and for large panels, where the weight and personal injury risks of glass are unacceptable. Also popular for photo frames and for frames which have to be mailed-out without expensive packaging.

Q. I've Heard a Lot About 'Static' Problems

Yes, most plastics develop a static electric charge during processing. This usually becomes obvious when the protective (cling-film) layers are removed. This can be minimised by maintaining correct humidity (55% RH+) and by cleaning with a damp, lint-free cloth (do not 'polish' plastics with a dry cloth - this just increases the static problem). There are various earthing devices available including a very good antistatic brush (JP to provide details). There are also cream polishes available to reduce static build-up.

Q. I've Heard that Plastics Mark and Scratch Easily

They are certainly softer than glass and require greater care. The lower quality plastics mark quite easily and it is wise to leave the protective film on the outer surface as long as possible, even after frame assembly. Acrylics are tougher, but can still be damaged by careless handling. Creams are available for polishing small scuffs etc out of acrylic - and also to reduce static build-up. There are abrasion resistant plastics available for critical work - see Artshield.

Q. How Do I Cut Plastics?

The most commonly used 1.25 and 2mm styrenes can be scored on both sides and snapped. Use a wall mount cutting system (see Fletcher-Terry and KeenCut) or a craft knife. Thicker plastics should be machine cut and are best bought cut-to-size. Cutting shapes etc requires proper tools and practice and is best left to your supplier.

Q. I've Heard that Plastic Should Not be Used for Certain Artwork

Yes - do not use plastic over pastels, chalk or any other powdery medium. Care is also required with textiles etc. Main problem is static build-up when the plastic is cleaned. This can cause very strong attraction and lift particles (of pastel, chalk, textile etc) from the substrate and onto the inside face of the glazing. Not a good idea!

Q. Can I Get Diffused Reflection Plastics?

Yes - most of them are available with one side stippled to give an effective diffusion. The best plastics are available with a very fine surface and compare with the best diffused reflection glass (see Artshield).

Q. I've Heard of a Scratch-proof Plastic, What Is It?

These are plastics (usually acrylics) with very tough coatings on both sides. These coatings will withstand virtually all common causes of scratches and scuffs - you can even rub them with wire wool! The coatings also greatly reduce static build-up, thanks to their much lower friction coefficient. They also resist a wide range of chemical and environmental hazards. Our own Artshield range offers these benefits in clear, diffused and UV filtering versions.

Q. What about Light Transmission etc of Plastics?

Styrene is very similar to glass of the same thickness, reflecting <8%, absorbing <2% and transmitting the balance (>93% max). Although colouration is not a real issue, acrylics win here - and can be as good as waterwhite glass in this respect. UV light filtration is similar to glass - i.e. unless specially formulated as such, they are not UV filters. When formulated as such, UV filtering acrylics are very good, typically blocking out 98% of harmful UV light. Polycarbonate sheet does filter UV quite effectively, but in the process is degraded and eventually goes milky white.

Q Is UV Cast Acrylic a Coated Plastic?

No. UV Cast Acrylic is an acrylic (PMMA) sheet and the UV filtering medium is mixed in prior to production. It may be cleaned with a moist, lint-free cloth - and in the event of scuffing etc creams are available. Our UV Artshield is a UV acrylic with abrasion-resistant coatings on both sides and can be cleaned using all the usual methods as it is very difficult to damage.

Q What's the Best Way to Clean Styrene (or any other plastic)?

Carefully! Unless the surface(s) are scuffed or damaged, use just a damp, lint-free cloth (to avoid static build-up). In the event of surface damage, you may try a polishing cream - but these are generally best used on Acrylics. Our Artshield range can be cleaned by any of your preferred methods as it has extremely tough surface coatings.

<< Back to FAQ index