Polyurethane Ether Foam

Material Name
Polyether-Based Urethane Polymer

Brand Name
N/A - Polyurethanes are produced by multiple manufacturers.

Nicknames
Flexible Urethane Foam
Polyether Urethane Foam
Polyurethane Polyether Foam
Ether-Based Polyurethane
Etherfoam
Ether
Mattress Foam

Description
Polyurethane ether foam is an open-cell foam with exceedingly soft compression characteristics and a relatively low tensile strength. Its open-cell structure makes it permeable to air and water. Ether is the urethane polymer typically used in household and automotive furniture cushions; usually in a cream, light yellow or amber color.

Ether foam is not chemically stable, and the by products of its deteriation can be hazardous to some museum objects - especially if exposed for a significant period of time. Among the effects of deterioration are discoloration, powdering, changes in compression qualities and chemical off-gassing. Note the discoloration visible in the used sample photographed above.

Applications
Ether is generally not recommended for use in the context of art handling/preventative conservation. Though readily available among foam suppliers, ether's unstable nature makes it a risky material to use in an enclosed container, or long-term in any environment. Its relatively low surface tension can also call into question its suitability as a cushioning material in many cases, depending on the static load. For a more accepted form of polyurethane in the art handling field, see polyurethane ester foam.

Ether vs Ester
Ether is very similar in manufacture and appearance to polyurethane ester foam, another urethane polymer, and the lack of brand names combined with casual labeling can complicate the identification of polyurethane foam offered by some regional foam suppliers.

Ether was developed approximately a decade after ester to meet demands for softer, more flexible cushioning, a better reaction to wet environments, and somewhat lower manufacturing costs. It has a slightly larger cell structure than ester, and is less resistant to punctures or tears. Despite the larger cells, however, ether looks and feels smoother, with a more uniform surface texture. In contrast, ester tends to look more textured, with a little sparkle, and feel rougher, stiffer, and more dense to the touch.

Although two distinct gray colors are shown in the photo below, ether and ester can at times be found with nearly identical charcoal coloration. In such cases, it takes a trained eye to spot ether foam, and sometimes a pinch as well.


See this link for more information on the differences and backgrounds of ester and ether, provided on The Foam Factory website. More technical information is available online in the DOE report prepared by J.P. Madden, G.K. Baker, and C.H. Smith, "A Study of Polyether-Polyol- and Polyester-Polyol-Based Rigid Urethane Foam Systems."

Possible 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
Glue Gun - Limited facility with hot glue, due to very fragile cell walls breaking down. Large globs of glue needed to form an effective grip rather than long beads.
Spray Glue

Thermal & RH Properties
Ether is not watertight, and offers no relative humidity protection. Its thermal insulation has been rated higher than that of standard Ethafoam or PolyPlank, but considerably lower than polyurethane ester foam.

Stability
Relatively unstable compared to other foams available, including polyurethane ester foam.

Safety
See the attached Polyurethane Ether Foam Material Safety Data Sheet.

Forms
Ether is often manufactured in buns at 40' x 8' x 8', and cut into smaller sheets for other forms by foam fabricators. It is available in sheets as thin as 1/4", and as thick, long and wide as a full bun allows.

A special formulation called Dryfast is typically used in outdoor furniture and boat cushions.

There is a wide range of colors available.

Primary Use & Background
Ether was developed soon after World War II, and has since been used in diverse industrial and household applications; most visibly in packaging, seat and mattress cushions, water filters, and audio speaker components.

Similar Products in this Database
Polyurethane Ester Foam