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Best practices in your mixing room

Friday, April 20, 2012 - 15:31
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Restoring a car to its pre-accident condition is a more complex procedure than it appears. Add to that making a profit in an ever-more competitive industry, and repairers face challenges daily. Like any problem, the best way to solve a large and complex dilemma is to break it down into its individual parts. By isolating and correcting those areas, gradually the problem will no longer look so overwhelming. One of the areas we must continually examine to control costs is in the refinish department.

It has been said that in painting, there are so many uncontrollable variables that painters should pay strict attention to those they can control. There are so many variables that can – no must – be controlled, but are often overlooked. Painters spend so much time mixing formulas, cleaning equipment, recycling solvent and focusing on the normal routine of working in the mixing room that areas they know should be checked or maintained are sometimes pushed aside to get the job finished.

Too often, however, the paint work suffers as a result. Some of the difficult-to-correct and costly mistakes, such as a corrupt bank, can happen even when slight errors are made, and the consequences may not be apparent until long after.


With the addition of new products, such as waterborne paint, there are advantages, but also challenges that must be faced and integrated into the routine. One of the areas that can present special challenges to productivity and profitability is the mixing room (Fig 1). .

Depending on your geographical location, paint mixing rooms are likely to have mandated regulations, and you should check for state and local requirements in your area. Whether your mixing room is a manufactured one attached to the booth or not, its ventilation needs to be maintained. The filters, both intake and exhaust, should be checked and changed regularly.

Solvent vapors are generally heavier than air, so they will lie at the bottom of the mixing room. The ventilation should be drawn off from the floor and brought in from the top or at the upper end of the wall.

The mixing room should be kept clean, and although this is much easier said than done in a busy paint room, it is still one of the best practices. The room should be kept clean from dirt, spills and clutter. Dirt in the room will almost certainly find its way into the mixed paint. To avoid that, the room should be cleaned on a regular basis.

The toner mixing rack should be maintained as well. The machine and all other potential spark-producing objects should be bonded with ground straps. Even static charges from plastic containers could be catastrophic. Empty containers should be disposed of as they accumulate, as mixing rooms can quickly become cluttered, leading to potential mishaps. Spills should be cleaned up, according to local requirements, immediately.


Two very good tips for paint room best practices are: 1) As materials are used up and new ones put in their place, the old labels should be placed on the clipboard in the mixing room, so that at a designated time a restock order can be placed. 2) Waterborne paint, which has a limited shelf life when opened, should be marked with the date it was opened (Fig 2). .

As toners or other supplies are used, a tracking system for restocking should be established. Though it may sound obvious, toners should be kept in a logical order on the mixing machine, and as soon as they are used, the spouts should be cleaned and their containers placed back on the mixing bank. If all the toners for a formula are taken off the mixing bank, or if a toner is not replaced as it is used, grabbing the incorrect one is more likely.

Paint materials are costly, and if an incorrect partly mixed formula must be discarded, it severely impacts profits. Toner lid fit should be checked regularly, as should the mixing bank for proper operation. Check that all the toners are mixing as they should. Those toners that aren't used as often as others may evaporate solvent from a poor-fitting lid, or a top that doesn't close completely because paint debris was not cleaned off.

Follow mixing formulas completely and carefully. Toner mixing guidelines have changed with the introduction of waterborne paint. Some no longer need to be regularly mixed, while others, both solvent-borne and waterborne, still have mixing recommendations.

Many paint manufacturers recommend that the toners be agitated for 15 minutes at the beginning of the day and at one other time during the day for 15 minutes. There are some coatings that should not be overmixed, so each painter should know and follow the recommendations of the manufacturer for its specific product.


Keep mixing scales clean, level and calibrated at all times (Fig. 3). Some scales have leveling feet that can be adjusted. If the scale does not have a level bubble, the scale should be adjusted with a small torpedo level, both with the pan off and on, to make sure that the pan supports are not bent and are holding it at level. .

Some scales will indicate a fault code such as "L" when the scale is out of level. Both the pan and paint table should be kept clean. Though a scale will zero out the weight of a spill, if the paint is not in the can, it is not in the mix.

Calibrate the scale occasionally according to the manufacturer's recommendations. If this is something that you do not have the tools or knowledge to complete, your jobber will likely be able to do it for you. If the scales pan has dried paint all over it, it could be either out of level or out of calibration. The accuracy of a scale, especially when mixing small amounts of paint, is critical to the color match.

In fact, some scales are so sensitive that the manufacturer recommends that they be turned on and let "warm up" for 30 minutes before use, especially when large temperature changes have occurred.

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