How to Keep My Plexiglas Window From Fogging

Plexiglas is installed in many applications where weight is an issue.

Designed as a lightweight and shatter-resistant alternative to glass, Plexiglas is a synthetic, polymer-based, plasticized resin. Because Plexiglas is a plastic, it is prone to abrasion; even micro-abrasions not visible to the naked eye will trap moisture, causing excessive condensation, or fog, to form. To prevent Plexiglas windows from fogging, care must be taken when cleaning the surface to prevent scratching; once damaged, the surface must be repaired.

Things You'll Need

• Hose
• Soap
• Sponge
• Rubbing compounds
• Soft cloths
• Sealing polish

Instructions

1. Rinse the Plexiglas thoroughly with plain water from a garden hose to remove as much loose dirt as possible. Wash the Plexiglas with mild soap and water and a nonabrasive sponge. Allow the surface to air-dry.

2. Examine the Plexiglas surface. For deep and readily visible scratches, apply 100-grit rubbing compound with a clean, soft cloth. Work the compound aggressively, with your hand, into all areas of the surface with a circular motion, coving an 8-inch area at a time. Overlap each 8-inch section by 2 inches to ensure total coverage. Repeat the polishing procedure with a 300-grit followed by a 600-grit rubbing compound. If there are no deep or visible scratches, begin the resurfacing process with the 300-grit compound.

3. Wash the surface of the Plexiglas thoroughly with soap and water. Allow the surface to air-dry.

4. Apply a protective sealant polish approved for Plexiglas to the dry surface in the same overlapping circular motion with a clean cloth.

5. Prevent the surface from developing new scratches by reapplying the sealant as often as directed by the product manufacturer to maintain the protective coating. Always rinse Plexiglas with plain water, to remove loose dust and dirt, and then wash the Plexiglas with soap and water before reapplying sealant.

Tips & Warnings

• An electric buffer will help speed up the job when refinishing larger areas.

• Avoid abrasive cleaning materials, such as paper towels, when cleaning Plexiglas.

• Plexiglas is highly susceptible to swirl marks from incorrect buffing; do not use an electric buffer on Plexiglas unless you have extensive experience with the tool.

References

• “The Essential Boat Maintenance Manual”; Jeff Toghill; 2001
• “The RV Book”; Mark J. Polk; 2007

Resources

• Ridout Plastics: Care and Cleaning of Plexiglas Acrylic Sheet