We tried three scratch-removal systems, above. All are suitable for minor damage, but serious scratches may require window replacement.
Articles
Scratch-Off was featured on aviationconsumer.com in May 2006. Below are some excerpts from the article.
Glass Scratch Removers: Scratch-Off Works Best
None of the products tried work miracles, so avoid damage in the first place. Otherwise, patience and elbow grease—plus a power buffer—will yield decent results.
By Cory Emberson
Nothing looks better on an airplane than fresh glass and few things short of structural damage look worse than beat-up, scratched windows and windshields. Damage to aircraft windows is more than a cosmetic challenge, too—it can compromise flight safety by limiting your ability to see traffic or even the destination airport. Throw in a little rain or window fog and you can be blind.
While many aircraft detailing companies specialize in removing scratches from aircraft windows, a number of products on the market purport to allow spot repair of damage glass by the do-ityourselfer. We recently tested a few well-established scratch removal systems to see how well they repaired some worst-case scratches. We learned that the product directions must be followed to the letter and learned that Harry Callahan was right—a man’s gotta know his limitations.
How We Tested
We used a brand-new acrylic window intended for a Mooney 201, unused by a local shop customer. We divided the glass into four sections with masking tape and identified the scratch removal methods on the tape. Two sets of scratches were inflicted on the glass: a severe scratch produced by three passes of a ¼-inch common screwdriver blade and a separate single scratch several inches below it. (And yes, there was cringing.) The test scratches were the only blemishes on this acrylic, making the evaluation of the marks and the repair attempts as clean-cut as possible. Half of each section was covered by paper for comparison after the test.
Because the major scratch removal products are not perfectly comparable—all were applied using power tools and one (Novus) was also applied by hand—minor variations in the results were expected and observed. Novus is generally applied by hand, with power application as a choice for severe scratches. Digging into the Plex with a screwdriver qualified as severe, so we used both application methods. Even the single scratch was evidence of more damage than we normally see on an aircraft window. So we offer a caveat to account for this: The hand-applied product did not completely remove the severe scratches and, as a corollary, more was expected of the power-assisted products.
Scratch-Off
The Scratch-Off system uses four progressively finer compounds matched to two different foam pads which are attached to a backing plate for use on a power drill. The standard Scratch-Off kit, with enough product for one aircraft windshield, retails for $34.85; the deluxe FBO-sized kit, enough for several aircraft, sells for $66.50.
Which compound you start with is determined by the extent of the damage— gouges and chips will take the full course of treatment while hairline scratches, hazing and swirl marks may be repaired with the two finer compounds. The two coarser compounds are identified with yellow labels, matching the yellow foam pad: SO-1 (Micro Cut) and SO-2 (Micro Lite). They are designed to cut and remove deep marks, while the compounds used with the white pads, SO-3 (Micro Brite) and SO-4 (Microsheen) are used to remove swirling and for high-gloss polishing.
The first step calls for wet sanding with 600-grit sandpaper, which is not included in the kit. Take your time with this product as well and keep the RPMs below 1200. If the acrylic surface starts to overheat, spray the area with water and reduce the RPMs. It’s important to note that this product is not recommended for use on pressurized aircraft. Any window work on pressurized airplanes should be done by professionals.
A side note about equipment usage: The Makita orbital sander we used didn’t come with the thin open-ended wrench needed to remove the back plate. We had to buy one of those separately to get everything taken apart. While using an orbital sander and an angular polisher may be the best method for products like Micro-Mesh, it required an extra purchase at the home supply store. In our view, the ability to use more common tools would not only reduce the cost to the consumer, but would widen the field for use of this product.
