Variety of products available to remove paint form your aircraft
By Joe Escobar
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."
There are a variety
of abrasive strippers available on the market today. These offer the benefit of removing the chemical component from the de-painting process. In addition, some of them can be safely used on composite structures. One factor that needs to be kept in mind when working with abrasive strippers is migration of the media. All open areas of the aircraft should be masked to prevent the media from getting into areas of the aircraft that would be detrimental.
There are varying types of media available to remove paint. A number of manufacturers offer plastic media. ArmaKleen offers a sodium bicarbonate product for abrasive blasting. Wheat starch has even been developed for use by ADM/Ogilvie and is marketed as EnviroStrip.
Laser paint removal
A new technology in the area of paint removal is the use of lasers. General Lasertronics Corporation has developed a laser application for surface cleaning and de-painting. The system has a self-contained waste capture and disposal system and can be manually or robotically operated. The company has developed a portable unit by delivering the laser beam to the work surface through fiber optic cables with an attached workhead. The workhead can be as much as 150 feet from the laser source.
In a laser-based paint removal system, a pulsed laser beam is directed onto the surface at a calculated energy level. It breaks down the paint and primer coatings and produces a minimal waste stream.
Ultimately, there are many factors to be considered when selecting a paint stripping method. Although the costs for materials and equipment may be easy to determine, other factors come into play such as production rates, flow times, labor rates, facility requirements, and waste disposal.
In the end, the each stripper needs to be evaluated on a case-by-case basis. What might work well for one facility may not work well for another. All factors such as cost, ease of use, exposure danger, and disposal methods need to be factored when choosing a paint stripping product.
Safety tips to remember when stripping
Stevens Aviation offers the following safety tips to keep in mind when using chemical strippers.
- Always keep the floor wet with water while spraying stripper
- Follow aircraft and stripper manufacturer's recommendations while stripper is being applied
- Always wear all protective gear during the stripping process
- Always keep at least two personnel in bay while spraying stripper
- When steaming stripper off, always use four men
- Be aware of EPA/OSHA requirements as well as local/state regulations when stripping
For more information, please contact Denise DeYoung or Chuck Yon at
Stevens Aviation, Inc.
600 Deleware Street
Greenville, SC 29605
FAA Advisory Circular 43-205
Guidance for Selecting Chemical Agents and Process for Depainting and General Cleaning of Aircraft and Aviation Products.
995 Mill St.
The ArmaKleen Company
469 N. Harrison St.
Princeton, NJ 08543
Eldorado Solutions, Inc.
8935 North Meridian St.
Indianapolis, IN 46240
374 S. Milpitas Blvd.
Milpitas, CA 95035
Henkel Surface Technologies (Turco)
32100 Stephenson Highway
Madison Heights, MI 48071
2135 Skytop Drive
Stone Mountain, GA 30087
Randolph Products Co.
P.O. Box 830
Carlstadt, NJ 07072
131 1/2 Lynnfield St.
Peabody, MA 01960
P.O. Box 243
Eliot, ME 03903
TBM/Aviation Fluids Service
950 Kingsland Avenue
St. Louis, MO 63130