FeltCrest®
compressed reticulated polyurethane foam

Crest FeltCrest compressed polyurethane foam is a unique, environmentally friendly, flexible foam material that has been permanently compressed to a predetermined thickness. It is made from a wide selection of uncompressed foams manufactured by Crest. For each application, a foam is selected which exhibits the desired properties, then sliced to the proper precompressed thickness. The sliced foam sheet is then permanently compressed through a precisely controlled thermal setting process to form FeltCrest.

Typically, Crest Foam's FilterCrest highly controlled pore size reticulated polyurethane foams in polyester and polyether grades are used for producing Feltcrest materials (See Technical Product Bulletin No. 101). Non-reticulated foam may also be used depending upon application.

Crest FeltCrest compressed foam

Typical advantages

Feltcrest materials exhibit many unique characteristics and offer special advantages. Among these advantages are uniform texture, high strength_, and excellent filtration properties. Lint-free characteristics permit use of Feltcrest materials for many applications for which other materials are not suitable. Cost-effectiveness another important consideration is also a key advantage of FeltCrest materials when compared to traditional fiber felts. When compared to conventional filtering media such as fiber felts, glass fiber, woven and non-woven fabrics, and paper, Crest Feltcrest foams exhibit many superior properties and offer substantial advantages:

• HIGH VOID VOLUME AND UNIFORM POROSITY are ideal properties for reservoiring and metering applications, among others. Depending upon compression ratio used to produce FeltCrest from FilterCrest materials, void volumes as high as 95% are possible. The compression ratio determines Feltcrest 'S properties for high efficiency storage and delivery of liquids of different viscosities and types.

• NON-DIRECTIONAL CHARACTERISTICS AND UNIFORM TEXTURE are ideal for ink rollers. There are no weft and warp directions, machine or cross machine directions, permitting FeltCrest's orientation in any length/width plane.
  
  
• SUPERIOR FILTRATION QUALITIES result from the ability to custom tailor Feltcrest with specific compression ratios and finished thicknesses. The higher the compression ratio, the more cells per inch of thickness, resulting in a more rigorous flow path and more impingement surfaces to trap particulate matter.

• FELTCREST FOAMS EXHIBIT EXCEPTIONAL BREATHABILITY, wicking, capillary action, and high strength while maintaining high void volume and fine cell diameters.

• LINTING PROBLEMS ARE VIRTUALLY ELIMINATED with Feltcrest which is made of a continuously connected strand structure with no beginning or end. Without finite strands to shake loose (as in fiber felts) linting does not occur.

Typical applications

Most applications for FeltCrest compressed foam are for filtration, reservoiring, metering, wicking₁ gasketing, backing, cushioning, and sound absorption. A desired property for these applications is for small cell diameters (finer pore sizes) to increase capillary action or to trap fine particulate matter. Finer pore size foams also have thinner polymer strand thicknesses and higher specific surface areas which enhance the foam's properties. For these typical applications, selecting the finest pore size FilterCrest foam for compressing into Feltcrest is usually recommended.

Physical/mechanical properties

The compression felting process used to produce FeltCrest foam changes many of the physical and mechanical properties of the initial uncompressed foam. Typical changes include:

1. Compression resistance properties (measured as compression force deflection) increase dramatically with increasing compression ratio; the higher the ratio, firmer or harder the resulting Feltcrest.
2. Tensile and tear strengths increase dramatically with in creasing compression ratios. This is due to increased density of the compressed foam.
3. Specific cell diameter is decreased in the compressed direction, thus increasing the number of cells in that direction by a factor equal to the ratio of uncompressed to compressed thickness (also called compression ratio or "firmness"). Higher ratios add more cells per inch in the compressed direction, thus higher resistance to fluid flow and lesser void volume.

Compression ratio void vs. solid comparison

The percentage of void Vs. solid volume in Feltcrest compressed foam is a function of the compression ratio used to produce it from FilterCrest foam. In the three photos above, the uncompressed FilterCrest foam (shown on the left in each example) exhibits 97% void volume and 3% solid volume.

In the comparison photo at left, at a compression ratio of 3 to 1, the compressed mass on the right is three times greater than the uncompressed foam on the left, resulting in a 91% void volume and 9% solid volume. The middle comparison photo shows Feltcrest at a compression ratio of 5 to 1 which has an 85% void volume and a 15% solid volume. The comparison photo at right shows Feltcrest at a compression ratio of 10 to 1 which, even though highly compressed, still has a very high 70% void volume.

Safety considerations for FeltCrest materials

When used properly, Feltcrest polyurethane foams offer outstanding advantages for a wide variety of applications. However, as with all polyurethane foams, when exposed to intense heat, open flame, or other ignition sources, these materials can ignite and burn rapidly. Care should be taken to properly handle, store, and p Consult factory for additional information.