ASTM E96: Wet Cup Test - Breathability

A standard test for determining vapor transmission through a medium.


In moist environments or areas where mold and mildew growth are a concern, often times it is helpful to increase the "permeability" of a wallcovering. A wallcovering with higher "permeability" will allow the transfer of water vapor from the wall cavity out into the open air of the room. Wallcovering and other barriers put onto a wall can sometimes trap water that is behind a wall cavity, which could increase the growth potential of mold.

IMPORTANT NOTE: in all cases the growth of mold and mildew are caused by excess moisture in the wall cavity, and to permanently solve this problem the conditions creating moisture need to be eliminated. No wallcovering, even when permeable, should be considered a guaranteed cure for this problem. It also critically important to use a mold and mildew inhibitor in both wall primer and the wallcovering adhesive to assure best results.

Most commercial grade vinyl wallcoverings contain a solid sheet of vinyl as the face of their multi-ply construction. The vinyl face sheet is typically NON-permeable, meaning it is a solid sheet of plastic that water will not be able to penetrate or pass. One method which has been shown to effectively improve the passing of water vapor through a vinyl surface is to mechanically perforate the surface. This procedure which is commonly called "Micro perforation" or "Micro venting" has the wallcovering pass through a machine that physically punches very small holes through the material with pins. Manufacturers who perform this process can use different size holes, and different concentration of holes per square inch. The goal is generally to achieve a suitable transmission rate of water, which can be measured with several different standardized tests. Dreamscape has chosen to follow the guidelines put forward by the Wallcovering Association in their classification under WA-101

The Wallcovering Association WA-101 defines a minimum suitable transmission value of 8, which is measured by ASTM E96, Wet Cup Test and sometimes referred to as the "Water Method".

Our standard Dreamscape vinyl products can be perforated, and we have tested several different embossed Dreamscape Type II 20oz vinyls with varying results. Our results for ASTM E96 have yielded a range of values from 8 to 15. Note that 8 is the standard set forth in WA-101, and a transmission score of 0 would be scored for vinyl wallcoverings that are not perforated.

In addition to perforation solutions for vinyl wallcoverings, Dreamscape also offers a non vinyl product called Terralon, which by nature is already "breathable". Terralon has been shown to score as high as 16.5 in the ASTM E96, and this is without any perforation process. Terralon offers the highest permeable score we offer in the Dreamscape line and is therefore a great option for mitigating problems with mold and mildew growth behind wall surfaces.

ISO/ICC Certified Third Party Test Report for Terralon

Date: June 6th 2012File: ROYSON.A053112C
Sample Identified By Client As: Vinyl Sample SubmittedRef: Terralon ClearColor: Charcoal

Test Procedure

Water Vapor Transmission: ASTM E96
Procedure: B
Water Method: 70°F 50%Rh

Test Results

Permeance: 15.75 perms
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Test performed and certified by:

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