It is not necessary to repair each hole in a sign. When a hole does not damage the message or symbol and does not create the impression of a sloppy sign, then repair may not be needed. The following procedures can be used to make field repairs on signs.
Retroreflective Aluminum Sign Panels
• Remove all damaged background sheeting and legend. Usually this means about 1 in (25 mm) from the edge of the hole. A retractable-blade knife is a useful tool for this.
• Straighten the sign (flatten out the hole puncture nipple area) using a ball peen hammer and a flat surface (truck bed, trailer bed, or a fender dolly).
• Remove any additional sheeting damaged during straightening.
• Clean the entire area with xylol; then apply varnish maker’s and painter’s (VM&P) naphtha.
• Patch the hole or puncture on both sides of the sign backing material using 3M Company No. 425 UAL aluminum foil tape or equal. Use a squeegee to apply firm pressure on both sides of the sign. On large holes, start placing the foil at the bottom of the hole, overlapping each strip about f4 in (6 mm) in shingle fashion as you move up, and cover the hole area.
• Apply retroreflective background sheeting, extending it at least L in (13 mm) beyond the foil tape strips.
• Replace damaged legend with die-cut, pressure-sensitive, prespaced letters, borders, or symbols and firmly squeegee them into place.
• Seal edge of new background sheeting and legend with 3M Company No. 700 edge sealer or equal. If the sign is subject to snow burial and replacement sheeting extends to the edge of sign, place 3M Company transparent film (No. 639 or equal) along that top edge.
Instead of making small patches to signs with holes, a portable double-roller unit for applying a full-sized sign face to a sign blank in the field can be used. After patching the holes, remove the paper material protecting the adhesive backing. Carefully align the new sign face sheet with one edge of the sign blank and spread the new sign face over the sign blank as smoothly as possible by hand. Then crank the sign blank with new sign face through the portable roller unit to properly pressure-seat the new sign face. Seal the edge of the new sheeting if necessary.
Retroreflective Plywood Panel Signs
• Remove all loose wood on both sides of the sign and all damaged sheeting.
• Fill holes with wood filler, let the surface set, and sand smooth if you think the holes need to be filled for a field repair. Allow filler to harden. Small holes can be covered by foil tape without filling.
• Wipe areas with clean cloth.
• Cover holes on both sides of the plywood sign blank with 3M Company No. 425 UAL aluminum foil tape or equal. Apply firm pressure to the tape on both sides of the plywood sign back using a squeegee. On large holes, start placing the foil at the bottom of the hole, overlapping each strip about 1/4 in (6 mm) in shingle fashion as you move up and cover the hole area.
• Apply retroreflective background sheeting, extending it at least У2 in (13 mm) beyond the foil tape strips on the face of the sign.
• In the area covered by the patching, replace any damaged legend with die-cut, pressure — sensitive, prespaced letters, borders, or symbols and firmly squeegee them in place.
• Seal edge of new background sheeting and legend with 3M Company No. 700 edge sealer or equal. If the sign is subject to snow burial and replacement sheeting extends to the top edge of the sign, place 3M Company transparent film (No. 639 or equal) along the top edge.
• Lightly spray a sealing film of flat black enamel paint (use an aerosol can) over the aluminum foil tape covering the holes on the back of the sign panel. Be careful to keep paint off the front sign face, because paint will destroy the night retroreflec — tion. If your agency paints plywood sign backs some color other than black, use an appropriate color if possible.
