MAINTENANCE OF PLEXIGLAS®
Always dampdust Plexiglas® acrylic sheet. For best results, mix a solution of one teaspoon of dishwashing liquid, or other mild soap or detergent, and a pint of water; apply this solution to Plexiglas® acrylic sheet with an atomizer or spray bottle and wipe until dry and glossy smooth with a clean cotton flannel or jersey cloth. Do not use dishwashing liquid containing hand lotions, such as aloe or lanolin.
To clean Plexiglas® acrylic sheet, wash with plenty of mild soap or detergent and lukewarm water using the bare hand to feel and dislodge any caked dirt or mud. A soft cloth, sponge or chamois may be used, but only as a means of carrying water to the plastic. Rinse well.
Dry by blotting with a clean damp cloth or chamois. Rubbing a dirty surface with a dry cloth will scratch the material. In addition, rubbing builds up an electrostatic charge on the Plexiglas® acrylic sheet so that it attracts dust particles from the air. Wiping with a damp chamois will remove this charge as well as the dust.
Do not use window cleaning fluids, scouring compounds, leaded or ethyl gasolines, benzene, acetone, carbon tetrachloride, fire extinguisher or de-icing fluid, lacquer thinners, or other strong solvents. To remove tar, grease, paint, etc., use a good grade of VM & P naphtha, kerosene, or other aliphatic hydrocarbon compound.
Best buffing results are obtained with cotton buffing wheels. There are a number of standard commercial buffing compounds satisfactory for use with Plexiglas® acrylic sheet. These usually consist of very fine alumina or similar “abrasive” in combination with wax, or grease binders and polishing tallow. Both are available in the form of bars or tubes for convenience in applying to the buffing wheel. Such compounds are sometimes referred to as coloring compounds.
If the buffing wheels have been used before, remove any hardened tallow by running them against a sharp metal edge. Start the buffing wheel spinning and touch the stick of tallow to the wheel. Bring a bar of buffing compound in contact with the edge of the wheel for a few seconds. Apply the edge of the spinning wheel to the sheet surface very lightly. Keep it moving over the surface and put only light pressure on the buff. Excessive pressure may heat and soften the plastic. Buff along and across any scratch and continue buffing until scratches have been removed. Finally, remove the buffing compound from the Plexiglas® acrylic sheet with a clean buff and apply a coat of wax.
If scratches are too deep to be removed by buffing alone, it is sometimes necessary to use sandpaper. Sanding should not be used unless some type of mechanical buffing equipment is available, since hand polishing is not sufficiently effective to restore luster to a sanded surface.
Since sanding or excessive buffing may introduce objectionable optical distortion, it may be better to leave in deep scratches.
If, after washing, the Plexiglas® acrylic sheet surface shows minor scratches, most can be removed or reduced by application of polish. To apply polishes, use a small pad of soft cotton flannel dampened with water. Rub the sheet along the length of the scratches with a back and forth motion (or use a circular motion). Avoid excess rubbing on any one spot. Several applications may be necessary, but most minor scratches can be reduced and the clarity improved within a relatively short time.
After waxing, wipe with a clean damp cloth to remove static charges that may attract dust particles. Do not use household spray waxes, as many of these contain agents harmful to the surface of Plexiglas® acrylic sheet.
Where sanding must be done, the finest grade sandpaper that will remove the scratch or other defects (no coarser than grade 320) is used first. The paper is wrapped around a hard felt or rubber block and the area rubbed lightly using water, or soap and water, as a lubricant. Abrasive paper should be of the waterproof type. Sand with a free circular motion, using light pressure over the area of the scratch. An area having a diameter two or three times the length of the defect should be sanded in order to minimize local optical distortion. Initial sanding should be followed by similar treatment using progressively finer grades of sandpaper: grade 360A, 400A, and 500 or 600A. Wash the Plexiglas® acrylic sheet after each sanding operation. During each step the scratches left by the preceding grade of abrasives should be removed.
Scratches too deep to be removed by the hand application of cleaners are often readily removed by buffing.
Where a large amount of polishing is undertaken, ashing compounds may be used with power buffing equipment in place of hand sanding.