Mixing and storing paint materials in the open shop environment invite and practically guarantee faulty finishes. Investing in a dedicated mixing and clean area will save many hours of corrections later. In this section, we show details about this clean area, and how it and the practices used within help avoid dirt in the finish.
The mixing room. A clean area for mixing paint is paramount.
- A paint mixing room that is isolated from the shop environment and is well-lit and well-ventilated is ideal.
- The mixing room should be next to the spray paint booth. The best situation is a mixing room connected to the paint booth, either directly-connected or connected with a clean room vestibule.
- 10 microns filtration minimum.
- If allowed by local code, should have communications capability with the spray booth.
- Do not store polishes, compounds, waxes and associated products in the mixing room. These are a major cause of “fish-eye” contamination.
- Use a mixing room table dedicated to the purpose of mixing paint or cleaning the spray gun.
- Do not use the mixing table to store old, left-over paint, compound or polish. These products can end up on the bottom of a paint cup and eventually end up in a paint job.
- An ideal mixing table would have a stainless steel top that could be cleaned regularly during the day
- Do not use paper covers on the table. Paper fibers can stick to a gun cup and end up in the paint.
Material Handling and Storage
- Use only fresh materials.
- Keep all material in its original container tightly sealed with its original lid.
- Store all materials not being used in a cabinet. This prevents wrong substances from getting mixed up in the product to be sprayed. It also reduces the chance of spillage and creates a clean, safe storage area.
- Keep all storage cabinets closed. This prevents contaminants from collecting on a container and ending up in a paint job. It only takes a small pinch of dirt in a paint cup to destroy an entire paint job.
- Openers should be readily available for all types of containers. Using the wrong tool can damage a seal, leading to contamination or evaporation of important solvents.
- Do not leave solvent cans open.
- Do not leave hardener cans open. Moisture in the air combines with oxidizing agents to cause small granules to form and leads to improper drying or curing of the paint.
- Do not leave mixed or unmixed material open to become contaminated, even in the spray booth.
- Cover each container with the same lid that came off it. Switching lids causes contamination.
- Mix paints only in proportion the manufacturer recommends.
- Set out products in the order in which they are to be mixed to prevent mistakes.
- Do not use any additives unless recommended by the manufacturer.
- Use the same line of hardeners and reducers as the paint being used.
- Store throwaway mixing cups in a dustfree container, use once and discard.
- To avoid damaging paint cup, pre-mix paint materials in a separate can and then strain mixed paint into gun cup.
- Strain paint immediately before use to guarantee removal of any solid particles.
- Place paint strainer directly over paint cup, keeping airborne dust from entering cup.
- Use wire mesh or bonded woven nylon strainers for best results – 145 mesh size for solid color and metallic paint, 100 mesh for primers and more viscous materials, 80 mesh for very heavy materials and “metal flake” (this mesh will allow contaminants through).
- Keep new strainers in dispenser.
- Use only clean rinse solvent
- Chase with 125 psi air pressure