Take a little time now to save a lot of time later
It has been said that in painting, there are so many variables painters can't control, they must pay strict attention to those they can. The paint mixing room is one of these controllable areas. Painters spend so much time mixing formulas, cleaning equipment, recycling solvent and working in their normal routine that things they know should be checked or maintained are sometimes pushed aside to "get the job finished." Too often, the paintwork suffers as a result. Some of the more difficult-to-correct costly mistakes, such as a corrupt bank, happen when even slight errors are made, and the consequences may not be apparent until long after.
If you develop a process to routinely check the mixing room and handle all its variables, you can maintain consistent formulas and color match. This process does not need to be cumbersome or lengthy. In fact, when developing a process, you need to indicate how much time is necessary to complete the work. Painters, especially flat rate painters, need this information so they can use their production time as efficiently as possible. Apply the old adage about changing the oil in your car to properly managing your mixing operations: You can "pay me now or pay me more later."The mixing room
Depending on your location, your paint-mixing room is likely to have mandated requirements. You should check the state and local requirements to comply with them. Whether your mixing room is a manufactured one attached to the booth or not, its ventilation system should be maintained. The filters, both intake and exhaust, need to be checked and changed regularly. Solvent vapors are generally heavier than air, so they lie at the bottom of the mixing room. Ventilation should draw off the floor and be brought in from the top or at the upper end of the wall.
Keep your mixing room as clean as possible and free from dirt, spills and clutter. Dirt in the room will find its way into the mixed paint, so clean it on a regular basis.
Maintain the toner mixing rack as well. The machine and all other potential spark-producing objects should be bonded with ground straps. Even static charges from plastic containers can be catastrophic. Dispose of empty containers as they accumulate since mixing rooms can quickly become cluttered, leading to potential mishaps. Clean up spills immediately, according to local requirements.Check toner lids regularly, along with the mixing bank for proper operation. Toners that aren't used as often as others may evaporate solvent from a poor fitting lid or from a top that doesn't close completely due to paint debris that was not cleaned off.
SCALES: Scales should be kept clean, level, and calibrated at all times. Some scales have leveling feet that can be adjusted. If the scale does not have a level bubble on it, adjust it with a small torpedo level, both with pan off and on, to make sure that the pan supports are not bent and are holding the scale level. Some scales indicate a fault code such as "L" when the scale is not level.
Keep the pan and paint table clean. Scales will zero-out the weight of a spill. However, if the paint is not in the can, it is not in the mix. If the scales pan has dried paint all over it, it could be either out of level or need calibration.Calibrate the scale from time to time according to the manufacturer's recommendations. If this is not something that you have tools or knowledge to complete, your jobber likely can do it for you. The accuracy of a scale, especially when mixing small amounts of paint, is critical to the color match. Some scales can be so sensitive that the manufacturer recommends they be turned on to "warm up" for 30 minutes before use, especially when large temperature changes have occurred.
MIXING: The mixing of a formula should be done with care. Many paint manufacturers recommend that toners be agitated for 30 minutes at the beginning of the day and three other times per day for 15 minutes each. There are some coatings that should not be overmixed and some brands of waterborne paint that only require a slight rocking of the container before pouring into a formula. Each painter should know and follow the recommendations of the manufacturer for each specific product
TONER BANK: As noted earlier, toners should all be turning when being agitated. Some mixing machines have a yellow plastic piece that bounces as the paddle turns in the toner can, making it easy to see when it is not turning. Others must be checked more closely. Dented cans or cans whose lids don't fit properly may keep the toner paddle from mixing. Most mixing banks have room behind the toner that is used to store spares of a color. Store these spare cans upside down to minimize pigment settling. When a can stored in this manner is turned upright and the agitating lid is attached, it is easier to suspend the components than if they remain stuck to the bottom.SHELF-LIFE: Shelf-life is not an issue with most solvent-borne paints because they can last for years if they are kept from drying out. However, waterborne toners will go bad if they are not used in time. Painters should check with their jobber or manufacturer for their brand's time recommendation.
CORRUPT BANK: A corrupt bank occurs when a toner is poured off without being agitated or before it is in correct suspension. Though a painter sometime can spot a corrupt bank as the paint comes out, other times a corrupt bank is not so obvious. If a toner is poured off in this state, that formula mix won't match. But more importantly, the colors mixed with that corrupt toner are not likely to match either.
This mishap can occur without being noticed. The painter may look for other possibilities before discovering that the bank has one or more corrupt toners. Even if the painter suspects a corrupt bank, finding the bad toner or toners is difficult. The painter must keep track of the formulas that are a mismatch and correlate the common toners to narrow it down to the correct one or ones in order to replace them.You can see this is a difficult and tedious process, but it can be avoided by proper agitation. Some paint manufacturers recommend that new toners be placed in a shaker for as much as 30 minutes before attaching an agitation lid and placing it on the mixing bank.
POURING THE TONER: Though there are computerized pouring machines for precise mixing of formulas, most of us still do it manually. There are some techniques that can help with accuracy. Formulas, especially small ones, must be mixed precisely. Every number must hit correctly. Even if the computer can re-calculate the pour, there may not be enough room in the container. If the correct amount of paint was calculated, the recalculation will overmix the amount needed.
Hold the toner so the pour hits the center of the container. Do not rock the can back and forth to control the amount of paint you're dispensing. Instead, use your thumb or finger to allow the paint to freely flow out when the gate is opened. You can start the pour at a fast rate and then slow it down by partially closing the gate as the amount reaches the correct weight. Some scales may need to catch up with a fast pour, so be careful as you near the desired amount. Pour precisely. If you believe that +1 or –1 is OK, you may get away with that sometimes, but the times you don't will be costly.
LABELING: If the paint is mixed just before it is used and the precise amount is calculated and then used, there may not be a need for labeling. But if the paint is mixed on one day and used on another, even the next day, you must label the container. If there is more than one painter or if a painter's helper edges in some parts with paint while waiting for the job to be completed, the mixed paint must be labeled.
Also, note common colors like silver. Silvers may each appear to be quite different on the vehicles but can be hard to distinguish as liquids. Labeling is not only required by law, it's also a wise practice.
RETRIEVAL SYSTEM: Most shops currently retrieve paint formulas by computer. Whether it is retrieved from microfiche or computer, the equipment must be maintained and kept clean. Dirty, dark or damaged screens must be corrected. The bulb may need to be replaced to make it bright enough. On computers, the screen brightness often can be adjusted. On some screens, dried paint spots can be gently removed with a razor blade, while on others this technique should not be used. Ask your jobber for directions for cleaning. The easier it is to properly read the formula, the less risk there is for errors.
Conclusion: Make it a routine
It may seem that all of these procedures, if done as recommended, could keep a painter from being productive. Some chores, such as cleaning, maintenance and restocking, can be delegated to someone other than the painter; but other tasks must be performed by the technician. The bottom line, though, is that creating a process, attaching the appropriate time and carrying it out as designed will save valuable time. Mixing room routines can make a paint department more efficient and profitable by reducing the chance of color mismatches. With a well thought-out process, the variables that can be controlled will be.
