Variety of products available to remove paint form your aircraft
It's a fact of aviation life. At some point in time, an aircraft is going to require a new paint job. Part of the process involved with a new paint job is removal of the existing paint. Today, there are many choices in de-painting systems. These include chemical as well as abrasive removal choices. This article will look at some of those choices available now and some evolving technology in the area of paint removal.
Not so many years ago, the most popular method of chemically stripping aluminum skinned aircraft was methylene chloride. It is an effective stripping method that quickly removes old paint and primer. But alas, along with the benefits of this stripper were disadvantages that included health risks (it is a suspected carcinogen) to the operators. Eventually, the government stepped in and enacted legislation limiting the use of these strippers. In April 1997, OSHA regulations were established to reduce worker exposure to methylene chloride.
Alternative stripping methods
There are several alternative stripping methods to methylene chloride. They fall into two basic categories, chemical and abrasive. We will discuss some of the different processes available today.
The industry is switching over to lower toxicity chemical strippers. Although these are safer than methylene chloride strippers, they should still be treated with care. They must be handled, applied, and disposed of very carefully to avoid damage to the aircraft and injury to personnel.
Benzyl alcohol stripping
Benzyl alcohol and benzyl alcohol blends which include strippers such as Turco 6813 and 6813E, CB 1058, El Dorado PR 3140 and P3170, have been identified as paint strippers that don't contain Hazardous Air Pollutants (HAPs), and can be substituted for methylene chloride paint strippers. They can be used in conjunction with conventional strippers to strip hard-to-remove coatings.
Benzyl alcohol solutions can be divided into acidic and basic formulations. Basic (alkaline) solutions contain approximately 30 to 50 percent benzyl alcohol, 5 to 10 percent amine or ammonia compounds and has a pH of 11.0. Acidic solutions contain approximately 25 to 35 percent benzyl alcohol, 10 to 15 percent formic acid, and have a pH of 2.5. The acid solutions tend to react faster than the alkaline strippers and are generally safe for all metals except high strength steel or magnesium. Acid-based strippers can potentially embrittle high strength steel. As with methylene chloride strippers, non-metallic surfaces such as composites and rubber boots and seals must be masked off or removed when stripping.
One factor to consider is the increased time to strip, generally around 25 percent more time. In addition, temperature of the stripping facility needs to be maintained at a warm temperature due to the strippers' slow reaction rates below 65 degrees Fahrenheit.
Hydrogen peroxide strippers
Hydrogen peroxide strippers like El Dorado PR5000 and Turco T6881 use hydrogen peroxide that breaks down in use to form oxygen and water. They contain a mild odor and contain no HAPs. Although these products are touted as environmentally safe, keep in mind that the paint you are stripping off the aircraft may make the waste sludge a hazardous material, covered under applicable hazmat regulations.
Use care when applying stripper
Remember that chemical strippers can potentially damage plastic and fiberglass parts. Those parts should be removed, and the paint removed separately by hand, or the areas masked to prevent contact with the stripping agent. In addition, sealants may have to be re-applied after stripping.
Keep in mind that chemical strippers should not be used on fabric covered aircraft. Roger Lenhert of Randolph Products company states "Beware of any stripper that claims to be safe for use on fabric. The fact of the matter is that serious damage can occur if attempting to use a chemical stripper on fabric, and only physical removal like hand scuffing should be used."
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