Please choose the correct ending to complete the given sentence: Computers and Electronics: [header] How to waterproof fabric [title] Plan to waterproof your fabric on a dry, windless day. [step] 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.

Ending1: You should lower the humidity level by 30 or even 50 percent for optimal protection against rain. [title] Spread a waterproof liquid under the fabric. Ending2: If you are working inside, you could use a spray-on super-dry, as this will absorb most of the moisture from the wind. [substeps] The sealer should not work any lighter than 23-27 psi. Ending3: You can also cover the entire fabric with spray paint, at least twice a day. [title] Choose sealers formulated for dog diapers. Ending4: [title] Clean the fabric if it is dirty. [step] If the fabric cannot be washed, and it is only dusty or lightly soiled fabrics then clean it a vacuum or a brush.

Answer format: ending1/ending2/ending3/ending4