Application Technical Report ATR-1879
Activity:Repair & Maintenance Cleaning
Industry:Automotive Body Shops
Widget:Paint Spray Guns
Soils:Uncured Waterborne Paint
Method:Manual Parts Washing
Material:Aluminum, Brass, Stainless Steel, Plastic
Product:Mirachem 500 Cleaner / Degreaser
Performance improvement from using advanced aqueous cleaning technology versus water or traditional chemistries.
It is a common misconception that waterborne paint can be cleaned with water as effectively as with a cleaning product. This is much like washing clothes without detergent and saying that the stains come out just the same. It may be true some of the time, but not most of the time.
In this case study, the collision repair centers of a large automotive dealer chain were presented with the opportunity to replace water-only cleaning with Mirachem 500 Cleaner Degreaser.
An effective cleaning and maintenance program for paint spray guns not only keeps the equipment performing at optimal efficiency, it also improves the overall quality of the paint job by supporting an even spray pattern and uniform dispersal. Proper cleaning also extends equipment life and make job cleanup faster. .
Processes for spray gun and hose cleaning and will vary with the needs of the operation and the equipment being used. In general, however, the steps include:
1. Starting cleaning process immediately following use while paint is still wet
2. A “knockdown” cleaning step to remove excess excess paint
4. Detail cleaning
For this evaluation, Heritage-Crystal Clean representatives recommended the use of Model 1683 parts washers using Mirachem 500 at a 4:1 dilution at ambient temperature. Performance improvement over plain water was readily apparent and the aqueous solution was adopted.
It should be noted that the customer’s operation supported the application of both waterborne automotive finishes and solvent based primers and clearcoats. The customer maintains Model 1683 parts washers using both Mirachem 500 and lacquer thinner to remove both soils as appropriate.
1. When cleaning paint spray guns, it is important to understand the distinction between cleaning wet or uncured, paint, and cleaning dry or cured paint. Once dry, paint becomes resistant to most cleaning processes. If you consider that a durable, long-lasting finish is the desired result for an automotive exterior, it’s easier to understand why proper maintenance cleaning of spray equipment and lines is essential.
2. Aqueous cleaners are designed to remove waterborne paints. They will provide poor performance on solvent-based paints or inorganic sealers and top coats. Maintaining paint equipment used to apply these materials typically requires a solvent or thinner-based process. Most painting operations utilize both systems. Solvent-based cleaners should never be used to clean waterborne paint.
3. Caution should be when cleaning used near waxed or polished surfaces such as finished automotive exteriors. Cleaning products, including Mirachem 500 at higher concentrations, can disturb waxed surfaces and other organic finishes.
4. Use of specialized spray gun cleaning equipment like the Crystal Clean Model 1683 can provide improved efficiency and process automation. However, excellent results can also be achieved using general purpose sink-on-a-drum style parts washers, such as the Crystal Clean Model 2703, or even simple soak tanks.
5. Instruction manuals for specialized spray gun cleaning equipment often refer to cleaning solutions as “solvent”, regardless of whether the product being used is hydrocarbon or water based. Users should bear in mind that the appropriate cleaning fluid is a function of the the paint being removed, not the equipment being used. For the purposes of these instructions, the term “solvent” applies to either thinners or aqueous materials.
IMPORTANT: Solvent (hydrocarbon-based) products should never be used in heated cleaning equipment due to the risk of fire or explosion.
6. Instructions for use of paint gun cleaning equipment often refer to “dirty solvent” and “clean solvent”. In such cases, the equipment has two fluid reservoirs, one containing only virgin cleaning fluid (clean solvent), and the other containing used solution of cleaner and paint (dirty solvent). The dirty solvent is typically recirculated between the “dirty” reservoir and the working sink area if the unit.
7. Waterborne paints typically disperse well in aqueous solutions. In some cases, paint may come off in sheets or blobs. Care should be taken to make sure the circulation pumps are not clogged or damaged.
8. Care should be taken when cleaning plastic spray guns or parts to evaluate compatibility with the substrate materials. There is a small risk of deformation or discoloration in less-durable plastics if subjected to an extended cleaning cycle or soak time. Tools manufactured for industrial use and constructed with more durable materials, such as HDPE or other cross-linked polymers, should not be a concern.
9. Ensure that all spray gun parts are completely dry before returning to service. Cleaning product left behind on surfaces or in the lines can significantly impact paint quality.
10. Appropriate personal protective equipment (PPE) should also be used when by personnel working with or near hot materials or spray washing applications.