Waterproofing Cushions

Silicone waterproof coating may be applied to SunMate^®, Pudgee and Laminar cushions. The silicone coating provides an elastic, waterproof layer which is safe for skin contact, resisitant to odors and soiling, and won’t detract from the cushion’s support capabilities.

Applying Silicone - General Information

1. One tube of silicone will coat a 16” x 18” x 2” cushion.
2. The silicone may be applied directly to the cushion or to a fabric that is at least 50% cotton/polyester and glued to the cushion surface, as on a FIPS insert.
3. The silicone sealant provides a high-friction rubber surface.
4. Velcro^® will not adhere to silicone. If applying Velcro^® strips, first adhere a piece of fabric to the moist silicone. When the silicone is dry, glue the Velcro^® to the fabric.
5. When waterproofing open-cell foam, such as a SunMate cushion, cut off a 1/16" strip of the silicone coating at each corner so that air can move in and out of the cushion. If the cuts are omitted, air bubbles may appear between the cushion surface and the silicone coating and cause the silicone to peel off the cushion.

NOTE: Dow Corning 732 RTV silicone and GE Silicone II are two brands most often used to waterproof our cushions. GE Silicone II is available in white or clear and produces fewer fumes than the Dow brand. The two brands are not compatible, and should not be used together.

Preparation

Apply the silicone in a well-ventilated area. The Dow Corning 732 RTV silicone sealant releases acetic acid fumes while curing. Wear latex gloves, and cover the work area with polyethylene plastic. Be sure the cushion surface to be coated is dry and oil-free.

Application Instructions

1. Place half of the silicone tube contents in a paper cup or on a paper plate. Add an oil-based pigment if color is desired. Stir with a tongue depressor stick until well mixed.
2. Apply the first coat. Put half of the prepared silicone on the cushion. To obtain good penetration and distribution, hold the spreader vertically when applying the silicone. Coat the top of the cushion and over half-way down the sides.
3. Apply the second coat. Put the rest of the silicone on the top of the cushion. Hold the spreader at a 45^o angle so that the second coat will totally seal and provide a smooth surface to the cushion.
4. Let the cushion dry to the touch. It will take 30 to 60 minutes, depending upon the humidity.
5. Turn the cushion over and repeat steps 2 and 3.
6. Cut out 1/16" silicone strips at each corner so the air can flow in and out of the cushion. Cuts do not need to be made in the FIPS insert due to the large surface area.
7. Dust the cushion lightly with corn starch or a similar powder to reduce friction and make the surface smoother.
8. Refer to the FIPS manual for further details on finishing a FIPS seat.

Applying the first coat of silicone. Hold the spreader in a vertical position.

Applying the second coat of silicone. Hold the spreader at a 45^o angle.