Look for commercial air conditioning / heating system air filters. Some of them appear to be made of the same thing as far as I can tell. You might be able to just cut them up.
__________________ May the bridges I've burned light my way.
Not sure what you are using the Hygrolon for. I have it my terrarium to wick water up the wall of my tank. This is a woven cloth fabric. The orchids are attached to cork slabs that are against the Hygrolon for moisture and to keep humidity high. A plastic material would not do this.
The shelf-lining material is hydrophobic. Water would not stick to it, and would not wick up the material.
If you will have a misting system to wet the orchids planted on the Hygrolon substitute, you can use the heavy-duty landscape fabrics put down under mulch on large commercial installations. This sort of material is almost the thickness of carpet pad, and is not the landscape fabric sold at big-box stores. This sort of fabric is also used for living walls.
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Thanks bjmac and estacion.
Didn't know this product was a woven cloth material. I had planed to use it for a background or a drip wall. Will shop Glass Box.