Stephenson & Lawyer, Inc. - Foam Fabrication for Engineered Applications
Phone: 800-372-3172  ·  Fax: 866-372-8747  ·  3831 Patterson Ave., S.E.  ·  P.O. Box 8834  ·  Grand Rapids, MI 49518
Reticulation is a post process that removes the window membranes of the cell.
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There are two methods of reticulation: Thermal, called "zapping" and chemical, called "quenching".

Zapping - [ Z ]

Zapping is a process that involves placing a bun of foam in a very large vacuum pressure vessel known as a "zapper". The vessel is evacuated and filled with an explosive gas mixture. The gas is ignited and a controlled flame front passes through the foam, melting the window membranes and leaving the skeletal structure intact. Zapping works with both polyester and polyether polyurethanes.

The benefit of the zapping process is a smooth, clean polished cell stand. This can be important in a clinical application such as a defoamer in a blood oxygenator or other medical applications. Another benefit is that zapping works on polyethers which perform better in applications that require hydrolytic stability at evaluated temperatures. Zapping can be done on buns for producing sheets or logs for producing rolls.

Quenching - [ Q ]

Quenching involves running the loaf of foam through a caustic bath of controlled temperature, concentration and duration. The caustic solution attacks and dissolves the window membranes, leaving only the skeletal structure. The foam is then washed, rinsed and dried. One shortcoming of this process is that it leaves a trace powder in the foam, making it unsuitable for some clinical applications. Quenching is not effective in polyether polyurethanes.

One benefit of the quenching process is that it produces a rougher or more etched cell strand which holds liquids better due to surface tension. Another benefit is quenching produces softer feeling foam especially in higher porosities, which can be important for cosmetic applicators.

Contact a Stephenson & Lawyer Sales Representative to help find the right reticulated foam for your application, and for more detailed information on reticulated foams.

If you know what type of foam your application requires request a sample.

Specialty Industrial Foam®

(SIF) (Fine Porosity)

This material is a reticulated Polyurethane, available in 80 to 100 pores per inch, Z or Q.

SIF Fine Porosity
100 PPI - [ pores per inch ]
Used as a sound absorber in anechoic chambers, microphone windscreens, lint free wiper pads, filters, face masks, hospital comfort pads, powder puffs and applicators, plus many other applications. Available in colors.
Filter foam works as a depth loading filter, opposed to a surface loading filter, trapping dust particles within its cell structure. Because the reticulation process leaves behind the skeletal structure of the foam it is 97% void volume giving it a high degree of surface area for impingement of dust particles.

SIF Medium Porosity
45 PPI [ pores per inch ]
With its homogeneous and uniform cell structure, a foam filter can be engineered for pressure drop and filtering efficiency by changing its pore size.

Specialty Industrial Foam®

(SIF) (Filter Foam)

SIF Filter Foam is a reticulated Polyurethane, specially adapted to air and liquid filtration, in a range of controlled cells from 10 pores per inch to 100 ppi, Z or Q.

SIF Coarse Porosity
10 PPI [ pores per inch ]
Effective as a sound attenuator, humidifier belt, scrubber pad, washable filtration media for air conditioners, furnaces, small engines and automobile air cleaners, plus many other applications. Available in colors.

SIF Felt®

SIF Felt is a flexible, compressed, open cell urethane foam. It is made from a reticulated polyester or polyether filter foam by compressing the foam under heat and pressure in a heat press. This process densifies the foam and imparts a permanent compression set. Both Z and Q foams can be felted.

SIF Felt
The standard product is Grade 900 SIF Felt® which is made by compressing 90 ppi SIF®. By varying the pore size and the initial foam thickness to final felt thickness, specific performance and function requirements can be controlled. This thickness ratio is called the firmness of the material. A high firmness such as 20 (20:1 ratio) will give the foam a hard leathery feel. A firmness of 3 (3:1 ratio) will give the foam a soft and downy texture.


SIF II was developed for uses where stiffness and hydrolytic stability are key requirements. Like SIF®, SIF II is a thermally reticulated, fully open pore flexible cellular plastic.

30 PPI [ pores per inch ]
Based on unique polymeric building blocks which reinforce the structure, SIF II exhibits excellent strength properties especially evident in applications that require superior load bearing or firmness. Because it is a polyether, it is not readily attacked by dilute acids, or dilute or concentrated bases at normal temperatures. SIF II is available in pore sizes of 15 to 90 ppi.


Protectair is a completely open cell (reticulated) Polyether Poyurethane foam available in a range of 20 to 35 ppi.
Protectair 30 PPI
Engineered for filtration media in hydrolytically unstable envionments such as air conditioners and humidifiers.

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