Things You'll Need
Thermal lamination pouch or 2 lamination sheets
Clean cotton or canvas fabric
You can waterproof signs made from a variety of materials -- paper, cardboard and wood -- using either lamination or a water-repelling treatment. Lamination for small signs, or classroom schedules, is easy to do at home with a steam iron and standard laminating pouches. Larger signs with some depth are best covered in a water-repelling treatment, which can protect all surfaces of the sign.
Laminate a Sign Without a Laminator
Set the steam iron to a low heat temperature. Depending on the iron, your preferred setting should be "low" or number "2" or "3" on the dial. Allow the iron to heat while you gather the rest of the materials.
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Place your sign inside the thermal lamination pouch or between two lamination sheets. Center the sign within the pouch.
Cover the lamination pouch with the flat piece of fabric.
Iron the fabric surface to heat up the lamination pouch with the sign inside. Smooth over the pouch, working from the center toward the outside edges. You can lift up the fabric to check on your progress. Continue ironing until the lamination pouch heats completely and has adhered to the sign.
Wait for the lamination to cool. Use scissors to trim the plastic around the sign. Leave a thin border of laminated plastic around the sign to keep it secure.
Add a Water-Repelling Treatment
Set up a work area outside or in a well-ventilated room. Put down the drop cloth. Put on your work gloves and safety glasses. Wipe down all of the sign's surfaces to remove dirt and debris.
Shake the spray can of water-repelling base coat for one minute after the mixing ball inside starts to rattle. You should also shake the can periodically throughout the application process.
Apply two light base coats to the front of the sign from right to left, and then up to down. Hold the spray can 6 - 12 inches from the sign's surface. Wait 30 minutes for the base coat to dry. Repeat this step for all surfaces of the sign.
Shake the water-repelling top coat spray can for one full minute after the mixing ball has started rattling. Also, shake this can often throughout the application process.
Apply two light top coats over the dry base coat on the front of the sign. Apply the first coat in a left-to-right motion, and then apply the second coat in an up-to-down motion. Hold the spray can 6 - 12 inches from the sign's surface.
Wait two minutes and then apply two more applications of the top coat to the front of the sign. Wait two minutes between each application of the spray.
Repeat this process, including both base coat and top coat applications, on all surfaces of the sign. Wait at least 30 minutes before exposing the sign to water. For best results, allow the top coat to cure 12 hours before exposing to water.
Apply the water-repelling treatment on a dry, sunny day. This allows you to work outside and reduces drying time. Lamination also increases the durability of your sign, but a water-repelling treatment does not.
The water-repelling treatment will dry to a milky haze on fabric and leather signs.