Acrylic is an extremely versatile material which is used in a wide range of environments. Acrylic sheeting is available in a huge range of variations, including; clear, coloured, mirrored, frosted and even with a brushed aluminium effect.
Extruded acrylic and cast acrylic are the two main types of sheet acrylic you will come across. Although they may initially look similar, the two have quite different properties and one is also much more expensive than the other.
It is important to be aware of the differences between the two so you can pick the type most suitable for your needs.
Extruded and cast acrylic sheets differ mainly in their thermal and chemical properties which are caused by the manufacturing process. There are also several other differences as outlined below which you may wish to consider when choosing acrylic sheet for your home DIY project.
Key differences you should be aware of when working with acrylic sheets:
Due to the way the sheets are made cast acrylic tend to have slight variations in the thickness of the sheet whereas extruded sheets are much more uniform, with next to no variation. This makes extruded acrylic ideal for vacuum forming or situations where more detailed precise shapes are needed.
Cast acrylic has an isotropic response to temperature meaning there is a maximum shrinkage of 2% in all directions. It may be important to note that acrylic expands and contracts at a much greater rate than glass. Extruded acrylic, on the other hand, shows differences in shrinkage depending on the thickness and direction of extrusion.
Benefits of Extruded sheets
Benefits of Cast acrylic sheets
Both types of acrylic benefit from being durable and long lasting, showing excellent resistance to natural aging. Most manufactures will guarantee against noticeable yellowing for approximately 10 years.
Often it may not be made obvious which type of acrylic you are buying, especially online. Cast acrylic can be as much as double the price of extruded acrylic so if nothing is mentioned and it seems cheap, the chances are it is extruded acrylic.
Ponds need Pond Liners like a building needs a foundation. Among all the materials used for Pond Liners, plastic is the most versatile. It comes in two forms- pre-formed and flexible.
Preformed or rigid plastic liners are strong and long-lasting. They are made of polythene and other recycled plastic material. They do not develop leaks. They are more cost-effective than concrete. An average gardener can set up a small pond within one day using this liner.
Some of these models are fitted above the ground and some below the ground. Rocks and stones may be placed around it to give a natural look. The liners may be both UV- as well as frost-resistant. But they may be difficult to fit because of their different shapes and sizes.
Among the preformed models, the plastic liners may be cheaper than fiberglass, but do not offer support for free-standing use of the pond in a raised water garden. It is difficult to build around a plastic pond and support it evenly. When support is not uniform there is a danger that the plastic liner will crack.
Flexible Pond Liners are also available, like PVC (Poly Vinyl Chloride) and HDPE (High Density Poly Ethylene).These liners are not as flexible as rubber. Plastic liners are often used on large holding ponds when economy is a bigger concern than flexibility.
Large ponds require a Pond Liner that is safe for fish and aquatic plant life, inexpensive, easy to install and durable. Polyethylene fits the bill. Medium-density Polyethylene contains up to 5 percent carbon black, which makes it highly UV stable and suited to outdoor life. Twenty and 30 mm polyethylene can be custom-made according to your specifications.
PVC, or Polyvinyl Chloride, has excellent chemical compatibility and puncture resistance, lending itself to membrane liner applications. Some PVC liners contain UV stabilizers which protect them from breaking down when exposed to sunlight. PVC is not a crystalline membrane liner material, so it can elongate in all directions. It is the most cost-effective buried membrane and it has the longest successful use of liner material.
Another plastic is Polypropylene. It has special properties, like outstanding dimension stability, low coefficient of expansion and contraction, wide temperature seaming range, good chemical resistance and no stress cracking.
Plastic has its plusses and minuses, and the choice depends on the individual's requirements.