Material Name
Polyethylene foam
Brand Name
PolyPlank
Nicknames
Ethafoam (PolyPlank and other Pregis foam products are often called "ethafoam" by museum professionals, fine art service providers, conservation materials suppliers, and industrial foam suppliers due to their similarity and a long association of PE foam with the Ethafoam brand)
White foam
Etha
Ethylene
PE Foam
SenFlex (Another mislabel. Some industrial foam suppliers refer to the light-density PolyPlank LAM090 as "Senflex" - a non-recyclable polyolefin-based polyethylene of the same density from Sentinel Products Corp - or "Synflex" - which is either a pharmaseutical-quality liquid glucosamine or a thermoplastic tube used in hoses and wire casings, depending on the context. LAM090 is a nice soft material to work with, particularly for cavity packing, but it is good to be aware of what you are getting.)
Description
PolyPlank is the brand name of polyethylene foam plank manufactured by Pregis Corporation. It is a durable, flexible, closed-cell foam with excellent memory when used in an appropriate coverage and density for the load. It is water-resistant and impervious to most chemicals. It performs consistently through a wide range of temperatures. It is easily cut with knives, hot knives, band saws, powered foam rubber cutters, and table saws. PolyPlank adheres to itself and other polyethylene-based materials with heat-welding, or to most other surfaces with industrial-grade hot glue. The natural color of polyethylene is bright white with a soft translucence throughout. PolyPlank is not cross-linked, so it is easily recyclable.
Sheets and planks have a thin skin of 6 lb. foam on one face. The skin is an unbroken surface, but has a bubbly texture with approximately 1mm relief, and despite the absence of additives the foam feels waxy to the touch. The edges of the planks expose open cells where they have been broken. Individual cells range between 1-3mm diameter at medium density. Plank edges and other cut surfaces have a rougher texture than that of the closed skin. Both surfaces are generally considered too abrasive for making direct contact with sensitive surfaces, and require the mediation of a smoother material between the PolyPlank and the object, such as Tyvek Softwrap, Volara, or poly-sheeting for a few examples. This mediation can be achieved either by lining the foam or wrapping the object.
PolyPlank EXT220 and PolyPlank LAM220 appear very similar to Ethafoam 220, another brand name of polyethylene foam, but the two PE foams are manufactured with slightly different methods and chemical compositions. Medium-density PolyPlank has a larger cell structure on average, and the broken cell walls of cut surfaces feel rougher. It offers somewhat less resistance to compression and puncturing than Ethafoam of the same weight. PolyPlank LAM boasts two more light-density options than Ethafoam; 0.9 pcf and 1.2 pcf. The PolyPlank LAM090 (0.9 pcf density) is often distributed in the light gray tint pictured above, and sometimes mislabeled "SenFlex" by industrial foam suppliers.
2" material is relatively expensive per square foot, but less so than 2" polyurethane ester foam. The latter is also typically applied in greater quantity per container, thus magnifying the price difference.
Applications
PolyPlank is typically used in art handling as a versatile and chemically stable shock-absorption and vibration-dampening material applied in small amounts relative to the size of an object. In other words; multiple pads, strips or blocks are more common than continuous contact over broad areas.
It is more firm than open-cell foams of equivalent pcf densities, such as polyurethanes. EXT220 and LAM220, for example, are not soft enough to be highly recommended for cavity packing lightweight objects or, as noted above, full-contact cushioning over broad surfaces. However, LAM090 (0.9 pcf) is in fact soft enough to serve a cost-effective and chemically stable alternative to polyurethanes for cavity packing or contact with large surface areas. The equivalent standard product line of Ethafoam brand PE foam, by contrast, only goes as soft as 1.5 pcf.
The medium densities of PolyPlank carves well with sharp knives for precise contouring of cushioning pads. 220 is stiff enough to employ as yokes for medium-large diameter rolling tubes or guillotines for moderately sized sculptures. Heavier objects can be secured with pads & wood bracing, and with the further option of greater foam densities. EXT900 is typically reserved for support underneath objects weighing several hundred lbs or more.
It will also provide some thermal insulation when applied as lining for a container.
Common Fabrication Tools
Knife (deli knife, extendable box cutter, specialty foam knife)
Foam rubber cutter (electric) - For best results, mount cutter under saw table with an adjustable fence
Hot knife
Band Saw - For best results, use a scalloped or straight blade
Table saw - For best results, clean table saw blade frequently
Heat Gun
Glue Gun - Suitable with hot-melt or low-melt glue sticks
Thermal & RH Properties
PolyPlank has a thermal resistance (h·ft²·°F/BTU) rating of R-2.5 - R-3 per inch thickness, which is about half that of extruded EPS, and roughly a third that of polyurethane ester foam. PolyPlank is water-resistant, and possibly the same watertight spec as Ethafoam, but Pregis does not claim the latter. The exposed and broken cells of 220 can absorb 3% water by volume, but higher densities will absorb less.
Stability
Natural tint (white) PolyPlank is widely considered chemically stable and suitable for use in preventative conservation.
Safety
See the attached PDF, PolyPlank MSDS, for the material safety data sheet.
Forms
The most common form stocked in the art handling field is PolyPlank LAM 220, with a relatively medium density of 2.2 pounds per cubic foot, in 2" natural tint (white) sheets at 108 x 48", or 108 x 24" planks to store more easily with other polyethylene foams of higher densities. 2" material has a useful balance of dimensionality, stiffness, and ease of cutting. Strips or blocks cut from it can be quickly laminated into much thicker cushions as needed. LAM is made from thin layers of extruded foam planks laminated together. The layers are described on the Pregis website as 1/2" thick, but 1" layers have also been observed in the field.
Sheets and planks are not quite flat on the faces, tapering slightly at the two long edges. The long edges also tend to have concave surfaces and a manufacturer's stamp, so it is recommended to trim strips at least 1" wide off any factory edges and discard. The actual thickness of a single 2" plank can range between 2” – 2.25” approximately.
Other Sizes and Densities
Laminated units are available in the following densities:
PolyPlank LAM090 = 0.9 pcf.
PolyPlank LAM120 = 1.2 pcf.
PolyPlank LAM170 = 1.7 pcf.
PolyPlank LAM220 = 2.2 pcf.
They are typically manufactured in 1/2" - 3" thicknesses, and 108 x 48" sheets, but other dimensions can be custom ordered.
PolyPlank EXT is the same formula as PolyPlank LAM, but extruded in one piece rather than laminated, and at a slightly higher price. It is available in the following densities:
PolyPlank EXT170 = 1.7 pcf.
PolyPlank EXT220 = 2.2 pcf.
PolyPlank EXT400 = 4.0 pcf.
PolyPlank EXT600 = 6.0 pcf.
PolyPlank EXT900 = 9.0 pcf.
They are typically manufactured in 2 x 108 x 24" planks, but other dimensions may be available for custom order.
Other Variations
PolyPlank LEL is formulated with less than 10% LEL (low explosive limit) VOC, which meets military and other low residual blowing agent specifications.
PolyPlank Renew is made with 40%-60% pre-consumer recycled material.
PolyPlank SFT is formulated with finer cells for a softer surface texture.
PolyPlank Plus is a custom-ordered system of laminating foam with a variety of substrates, including foil, bubble, adhesive and cohesive films, paper, non-wovens, etc.
Primary Use & Background
PolyPlank-brand polyethylene foam was developed specifically for shock-absorption, vibration suppression, insulation & buoyancy in storing and transporting military, computer, and medical equipment, and other precision instruments.
Similar Products in this Database
Ethafoam
Plastazote
Polyfoam
Astro-Foam
SenFlex
Backer Rod
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