Pretreatment/Cleaning

Many products require a preparation step prior to painting. This step is commonly called pretreatment for new products and paint stripping for products that need rework.

Cleanliness of Parts
The first step for reducing waste in pretreatment is assessing the cleanliness of parts. Determine the sources of contaminates to reduce or eliminate them. Consider to what degree surfaces become contaminated with substances such as oil from machining, dirt from the manufacturing environment and oil from people's skin.

Cleanliness of the Process
Next, determine the cleanliness standard needed to satisfy the pretreatment process. Once contaminant sources are identified and cleanliness standards are set, determine which contaminants can be eliminated. Then, if contaminants cannot be reduced enough through process changes, assess the cleaning methods used.

Aqueous Cleaning Equipment Manufacturers Aqueous cleaning equipment suppliers offer a wide range of cleaning equipment and related accessories.

Get It Plated Right Fact Sheet Series
This fact sheet series focuses on causes and solution for the most difficult cleaning problems for metal product manufacturers and designers. Although the series was originally written for plating, most of the same cleaning principles applies to other coating operations as well.

Cleaning and Design for Plating Lists some of the more troublesome parts for metal finishers to electroplate.

Cleaning Processes A large utensil manufacturer set up a custom-cleaning step to help eliminate troublesome soils. Also shows the value of eliminating soils at their source, before cleaning is needed.

Dried-on Process Fluids and Fluid Combinations Films of dried-on process fluids interfere with the bonding of plating to part surfaces. This sheet shows how to avoid the problems associated with dried-on process fluids.

High-Temperature Processing Burns on Soils Oils, coolants and many organic liquids form a varnish or paint-like coating on part surfaces when heated or aged. This fact sheet discusses how to prevent such soils from occurring.

Holes, Seams, Threads, Recesses and Tubing Assemblies How to recognize and eliminate unseen pools of contaminates trapped in recessed part areas.

Particulate Contamination on Part Surfaces Explains how oversights that cause particulate contamination of parts before plating can be a costly mistake.

Selecting Materials for Plated Parts The type of metals used to construct a part can affect how easily it is cleaned and the part's physical condition after a finishing process.

Phosphatizing
Phosphatizing prepares the surface of metal parts for coating. The volume of water used to maintain the phosphatizing bath solution can be reduced by analyzing and controlling each bath's temperature, chemical concentration and pH level; and by recirculating the solution or rinse water to other baths where possible. An added benefit is the potential for reduced chemical use.

Conversion coatings are among the recent industrial chemical products to move away from phosphorus chemistries. Phosphorus-based conversion coatings contribute phosphorus to wastewater loading when process solutions and rinses go down the drain. In many cases, wastewater treatment plants must remove phosphorus (a nutrient which causes excess algae growth) down to 1 mg/L, costing the industry or city for treatment.

Metal Phosphatizing Operations Metal phosphatizing operations are a large industrial source of phosphorus in wastewater. When companies minimize phosphorus discharge from these operations they save by reducing chemical and water use.

Other Resources
Alternative Solvent Degreasers A number of degreasing and cleaning solvents are marketed as alternatives to chlorinated solvents. In general, these are medium-to-high flash point solvents formulated to remove oil and grease and, in some cases, soldering flux and wax. All have lower rates of evaporation than the chlorinated solvent they might replace. MnTAP maintains this list of alternative solvent degreasers as a service to Minnesota companies.

Gun Wash Unit Cost Calculator The Iowa Waste Reduction Center has developed this calculator to help collision repair shops calculate savings and payback of using gun washers.

Selecting a Still for On-site Solvent Recycling Become better prepared to select the right still for your on-site solvent recycling.

Solvent Distillation Cost Calculator The Iowa Waste Reduction Center has developed this calculator to help collision repair shops calculate the savings and payback of using a solvent still.

Solvent Recycling Equipment Many solvents can be reprocessed and recycled for reuse. Distillation is the most common method, but filtration can also be used. MnTAP maintains this list of solvent recycling equipment suppliers solely as a service to Minnesota companies.

Spray Gun and Equipment Cleaning System Suppliers Cleaning paint guns manually is time consuming, labor intensive, exposes workers to harmful solvents and paints, and can generate significant quantities of solvent waste. An alternative to tradition cleaning methods is an automatic cleaning system.

Industry Case Studies
McLean Thermal a Champlin, Minnesota, manufacturer was facing one-time service availability and water access charges of nearly $25,000. McLean Thermal worked with a MnTAP intern to determine the best way to avoid those changes and reduce water and chemical use.

Hoffman Engineering Saves $32,000 Annually by Reducing Water Use in Painting Pretreatment Hoffman Engineering reduced fresh water use by at least 3.5 million gallons per year, saving $32,000 annually.

Lou-Rich, Inc. Saves Over $42,100 by Reducing Water and Chemical Use Water used in cleaning and cooling operations was reduced by 8.9 million gallons per year through design improvements and monitoring.

Reducing Solvent Emissions in Painting Operations at Crenlo, Inc. Using a new paint-pail washer, converting to a HVLP spray system and using low-VOC coatings could save Crenlo approximately $162,000 annually and reduce annual VOC emissions by 109,000 pounds.

Soak Step Reduces Solvent Waste from Cleaning Paint Straining Equipment Crenlo, Inc., in Rochester, found that it was possible to reduce their solvent waste by 55 percent through adding a presoak step to an equipment cleaning process.

Solvent Waste Cut with Spray Nozzle Selection when Cleaning Paint Straining Equipment Crenlo, Inc. reduced solvent waste by 80 percent or 11,000 gallons per year and saved approximately $13,000 per year on solvent purchase and disposal costs.