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How to waterproof fabric
Plan to waterproof your fabric on a dry, windless day.
You will be working with spray-on sealers, which are sensitive to humidity. Also, if you are working outside and it is windy, you might get some dust embedded in your fabric.
Options are:
(1). You should lower the humidity level by 30 or even 50 percent for optimal protection against rain. Spread a waterproof liquid under the fabric.
(2). If you are working inside, you could use a spray-on super-dry, as this will absorb most of the moisture from the wind. The sealer should not work any lighter than 23-27 psi.
(3). You can also cover the entire fabric with spray paint, at least twice a day. Choose sealers formulated for dog diapers.
(4). Clean the fabric if it is dirty. If the fabric cannot be washed, and it is only dusty or lightly soiled fabrics then clean it a vacuum or a brush.
(4).