Material Name
Polyethylene foam
Brand Name
Ethafoam
Nicknames
White Plank
Etha
Ethylene
PE Foam
Description
Ethafoam is the brand name of polyethylene foam plank manufactured by Sealed Air Corporation (formally by Dow Chemical Company). It is a durable, flexible, closed-cell foam with excellent memory when used in an appropriate coverage and density for the load. It is watertight 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. Ethafoam 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 foam is brilliant, sparkling white with a slight translucence in thin areas, but black and blue are also available in a limited range of sizes. Ethafoam is not cross-linked, so it is easily recyclable.
Sheets and planks have a skin on each of the large faces. 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 1-2mm diameter at medium density. Plank edges and other cut surfaces create 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 Ethafoam 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.
Ethafoam 220 appears very similar to PolyPlank EXT220 and PolyPlank LAM220, another brand name of polyethylene foam, but the two PE foams are manufactured with slightly different methods and chemical compositions. PolyPlank has a larger cell structure on average, and the broken cell walls of cut surfaces feel rougher. It offers less resistance to compression and puncturing than Ethafoam of the same weight. PolyPlank LAM offers two more light-density options than Ethafoam; 0.9 pcf and 1.2 pcf.
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
Ethafoam 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. In fact, 220 is not soft enough to be highly recommended for cavity packing lightweight objects or, as noted above, full-contact cushioning over broad surfaces. However, it carves well with sharp knives for precise contouring of cushioning pads. 220 is stiff enough to employ as yokes for large 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. 900 is typically reserved for support underneath objects weighing several hundred lbs or more or in storage and mountmaking applications where it's rigidity makes it work almost like wood.
It will also provide some thermal insulation when applied as lining for a container, and the closed-cell structure makes it waterproof.
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
See this link for the updated Ethafoam Technical Data Sheet. Ethafoam has a thermal resistance (h·ft²·°F/BTU) rating of R-2.5 - R-3 per inch thickness, which is half that of extruded polystyrene XPS, and roughly a third that of polyurethane ester foam. It is watertight, so only through-punctures and unsealed joins or gaps between pieces will allow transmission of moisture. The exposed and broken cells of 220 can absorb 3% water by volume, but higher densities will absorb less.
Stability
Natural tint (white) Ethafoam is widely considered chemically stable and suitable for use in preventative conservation. Black-tinted Ethafoam has passed Oddy tests as well.
Safety
See the attached PDF, Ethafoam220-MSDS for the Material Safety Data Sheet provided by Dow. Ethafoam is manufactured with blowing agents that can be released from broken cells into the atmosphere when it is cut or melted. These blowing agents are toxic and technically flammable, but they will not combust by accidentally melting the foam with the tip of a hot glue gun, or by heat-welding to another piece of foam. A well ventilated workspace is recommended when fabricating to mitigate the minor toxicity.
Forms
The most common form stocked in the art handling field is Ethafoam 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 the higher-density planks. 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.
After 220, the next most common Ethafoam specs used in art handling are the heavier densities within the same product line. Here is the :
Ethafoam 400 = 4.0 pcf.
Ethafoam 700 = 7.0 pcf. (Formally 6.0 pcf from Dow, known as Ethafoam 600).
Ethafoam 900 = 9.0 pcf.
Two lighter densities are available as well; 1.5 pcf and 1.8 pcf. See the chart below for more information.
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. For the purposes of cushioning crates with moderately tight tolerances of fit, Ethafoam is often ordered from regional vendors with the skin skived off one side to produce a flatter face and a more consistent 2” thickness. It can also be skived into 1” thick planks, also with a skin on one side only. Small variations in thickness should still be expected in skived foam.
Other Sizes
See the spreadsheet below. Dimensions, densities, colors, and special characteristics overlap independently in availability.
Other Variations
Ethafoam AS is an anti-static formulation of polyethylene foam that meets EIA 541 requirements for static decay and surface resistance. Bright pink in color, it shares all of standard Ethafoam's shock absorption and insulation qualities.
Ethafoam M is formulated with less than 10% LEL (low explosive limit) VOC, which meets military and other low residual blowing agent specifications.
Ethafoam Synergy is formulated with smaller cells for a smoother texture; fine and ultra-fine.
This spreadsheet lists all plank-form Ethafoams available from Sealed Air in their manufactured dimensions prior to fabrication by regional vendors, with one exception: Ethafoam FS - with fire-suppressant additives for use in the airline industry - has not been included here. Mil Spec foam formally available from Dow but undetermined from Sealed Air is listed in gray. Common specs in bold.
Name | Thickness |
LxW |
Density |
Special |
Color |
Ethafoam 150 | 2" | 108x48" | 1.5 pcf | Standard Extruded | Natural |
Ethafoam 180 | 2" | 108x48" | 1.8 pcf | Standard Extruded | Natural |
Ethafoam 220 | 2" | 108x48" | 2.2 pcf | Standard Extruded | Natural, Black |
Ethafoam 220 | 1", 1.5", 2.25" | 108x48" | 2.2 pcf | Standard Extruded | Natural |
Etahfoam 220 | 2" | 108x32" | 2.2 pcf | Standard Extruded | Natural |
Ethafoam 220 | 1", 1.5", 2.25", 2.5" | 108x24" | 2.2 pcf | Standard Extruded | Natural |
Ethafoam 220 | 2", 2.75", 4" | 108x24" | 2.2 pcf | Standard Extruded | Natural, Black |
Ethafoam 400 |
1.5", 2", 2.5 | 108x24" | 4.0 pcf | Standard Extruded | Natural |
Ethafoam 700 |
2" | 108x24" | 7.0 pcf | Standard Extruded | Natural, Black |
Ethafoam 900 | 2" | 108x24" | 9.0 pcf | Standard Extruded | Natural |
Ethafoam Synergy P2 | ? | ? | 2.0 pcf | Fine Cells | Black |
Ethafoam Synergy P3 | ? | ? | 2.8 pcf | Fine Cells | Black |
Ethafoam Synergy P4 | ? | ? | 4.0 pcf | Fine Cells | Black |
Ethafoam 220 AS | 2" | 108x48" | 2.2 pcf | Anti-Static | Pink |
Ethafoam 220 AS | 2" | 96x32" | 2.2 pcf | Anti-Static | Pink |
Ethafoam M1 | 2", 4" | 108x48" | 2.3 pcf | Mil Spec | Black |
Ethafoam M1 AS | 2" | 108x48" | 2.3 pcf | Mil Spec Anti-Static | Pink |
Ethafoam M3 | 2", 4" | 108x24" | 4.0 pcf | Mil Spec | Black |
Ethafoam M4 | 2" | 108x24" | 6.0 pcf | Mil Spec | Black |
Ethafoam M5 | 2" | 108x24" | 10.0 pcf | Mil Spec | Black |
Primary Use & Background
Ethafoam-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
PolyPlank
Plastazote
Polyfoam
SenFlex
Backer Rod