The best painters today can precisely mix color based on given formulas and correctly match color the first time. Failing to do so can cost your shop valuable time and money.
Each department of a collision repair business should operate to make a reasonable profit. Though all departments should be constantly scrutinized and measured to monitor their productivity and profit, the paint department, especially, has many challenges that affect its ability to consistently produce a reasonable profit.Painters who have the ability to mix the correct color precisely to the formula requirements in the exact amount needed — and can also match the color the first time without the need for adjustment or repair — are valuable employees indeed.
Collision repair shops have not always had the ability to mix formulas on site. In addition, some of the simplest mixing techniques have not been consistently taught in collision repair schools. Also, when a new painter attends a manufacturer's paint school, it's often assumed that rudimentary mixing techniques have already been mastered, so the techniques are not covered in depth.
It was once said that paint training is often taught by the "tribal" method. That is, a new painter will watch and then try to mimic a good painter, with little discussion as to why certain actions were taken. In fact, many painters, by necessity, have become great mimickers of the painters from whom they watched and learned.While watching an accomplished professional can be beneficial to new painters, identifying and discussing specific techniques will help a new painter develop faster and become more consistent sooner.
The collision repair industry has recognized the need to develop and implement Standard Operation Procedures (SOPs) for many common operations, but seldom has a SOP for color retrieval and mixing been discussed. With the obvious cost benefits of using quality methods in the paint department, measuring up in the mixing room is critical.
Some of the mixing room decisions painters must be keenly aware of and always perform accurately include:
- Identifying a blendable color by locating the correct vehicle code, converting an OEM code to paint systems code, and using a variant deck.
- Properly mixing by calculating the amount needed, keeping it mixed, avoiding overmixing at all costs, precisely following the paint formulations that have been provided and using the correct pouring method during the process.
- Reducing correctly for spray conditions by choosing the right amounts of reducer and hardener, and properly reducing on scale or by parts.
- Choosing the proper undercoating, with the correct color and deciding on the proper amount necessary for the job.
Painters must perform all those tasks before making a sprayout panel that confirms if the color is a blendable match or not, and before deciding how many coats are needed for full coverage. These areas all impact productivity and profit in the paint shop and should be the first steps taken in the mixing room when preparing to paint. Failing to do so can cause problems later.
Identifying a blendable color
Though it seems it's one of the simplest tasks in the process of refinishing, color retrieval is often not done thoroughly or completely, resulting in an unacceptable color match. Doing this task successfully starts with the technician locating the vehicle color code. Finding the color code on some manufacturers' vehicles is easy: for Fords, the code is on the door and for GM it's in the trunk.However, finding codes for others is not so simple. For some vehicles, when the technician looks up where to find the code, the literature will give two to four possible locations.
Once the vehicle's code is located, it must be converted to the color code for your shop's paint system. Often paint companies will provide a computerized color retrieval system, which will get you close to the needed color, but there may be variations.
Since a manufacturer's original paint is applied at different locations under different conditions, a single color may vary slightly. When the proper color code for a vehicle is identified, the color variant should be checked against the vehicle. Often with today's more sophisticated colors, there will be between two and five color variants from which to choose. In addition to accurately choosing the proper variant, the technician must compare the variant color sample to a clean surface of the vehicle.In the past, by using normal, non-color-corrected shop light, this task could be difficult. With the development of handheld portable color-corrected lights, it's an easier task. After the proper color variant has been chosen, it is time to retrieve the formula and mix the color.
Mixing
Most mixing systems have either balanced colors (paint that can be sprayed directly onto a vehicle without adding a rosin/binder) or unbalanced (tints that need to have a rosin/binder added before spraying). If a mixing system needs a rosin/binder, addition of the proper amount of it will be part of the formula.
One of the first things a painter must do is calculate the precise amount of paint needed, by using a calculating formula provided in the computerized retrieval system, or by adding up the panels that need to be painted and the partial panels, which will be blended to determine the total paint amount.Though formulas may vary from system to system, and the painter should use the manufacturer's recommendations, a common measure is six ounces of paint per panel, per three coats. That means if you need to spray two panels (doors) and blend into a fender and quarter panel, you would need 12 ounces for the doors and six ounces for the blends (½ for the blend of the quarter and fender blend), for a total of 18 ounces.
If your reduction ratio is 1 to 1, you would have, when reduced, 36 ounces of ready-to-spray (RTS) color. The amount of clear also can be calculated with a formula. The painter will need eight ounces of RTS clear per panel to apply two coats of clear. This calculation is an approximation for medium-sized vehicles. The painter will need to adjust the amount to different sizes of vehicles, but it is a good estimate to begin with.
By mixing the precise amount of paint for each vehicle, a paint department can cut down on wasted material significantly, and in doing so can increase profits.
Once the amount of paint is calculated, the painter must make sure that the mixing bank has been mixed or agitated properly. The paint-mixing bank will have varying colors that will range from thin, fast-pouring colors to slow-pouring, thicker colors. There also may be different sized or shaped metallic flakes. These colors may separate when allowed to sit for a long time.Most mixing banks have self-timed mixing switches that, when activated, will turn all the colors at once for a time period of 15 to 30 minutes. Most paint manufacturers recommend that the paint be mixed at least twice a day (first thing in the morning and again at midday). Though paint should be mixed regularly, most paint manufacturers recommend against continually mixing paint, especially metallics. Continual mixing causes "shirring," the changing of the metallic size or shape, due to the constant bombarding of the mixing paddles. Painters should read, understand and follow manufacturer's recommendations for mixing.
When a new mixing color is added to the bank, the new paint should be shaken before it is added, or mixed on the bank after it is added, so its color is the same throughout when the paint is used. If a color is not adjusted or mixed properly and some of the uneven color is poured off for a formula, that color could be permanently altered for the remainder of that can, and each consecutive mixed formula thereafter may be a mismatch.
Mixing the formula precisely to the amounts called for without over-or under-pouring is very critical when preparing paint. As pointed out earlier, some colors are more viscous than others and may pour faster or slower than others. In addition, some colors are of higher strength than other colors, which means that even a slight over-or under-pour will cause the color to change rapidly.
When the painter is mixing small amounts of paint, the accuracy of the pour becomes more difficult to control. Some paint manufacturers have developed computer-controlled pouring machines, which are highly accurate for pouring small amounts. If the painter practices careful hand pouring, the results also can be accurate.
Correctly holding the mixing color can when pouring helps with accuracy. The amount poured out will be more accurate if the technician holds the can so the color can freely flow out when opened, and does not tip it back and forth to control paint flow. The rate of flow is controlled by how far open the paint gate control is depressed with the operator's thumb.By varying how far open the gate is, either large or small amounts of paint will flow out. When large amounts of color are needed, the gate can be opened widely, allowing large amounts to flow out. As the amount of color needed becomes less and less, the operator should allow the gate to close, permitting less amounts of color to flow out. If the can is tipped to control the flow, the amount of paint available to flow out will be inconsistent and less accurate.
Reducing correctly for spray conditions
Modern paint systems have a large selection of reducers and hardeners that can be matched to the prevailing spray conditions. Polyurethane paints chemically cure and dry through evaporation. Using heat, hardeners or reducers can regulate the rate at which these processes occur. The choice of reducer used will regulate the amount of flash time needed. These products do not affect the color or the match, but do significantly influence the cure and dry time.
On-scale reduction is now available with most computerized systems, which eliminates the non-measured reductions that were common in years past. The computer system also tracks individual painters and the number of errors that each may incur during a tracked period, thus revealing the painter's efficiency level.Undercoat selection
In the past, tinting of undercoat was widely recommended. In practice, however, it did not prove to be universally practical. Some undercoats, when tinted with the topcoat color or a color similar to the topcoat, did not cover with fewer coats. Instead, undercoats in a variety of colors or shades help produce the proper value under the topcoat.
Brand-specific sprayout panels that display three or four of the shades of that brand's undercoat will show a painter which undercoat is best suited for that color. A painter simply uses the sprayout card produced by the paint manufacturer. When full coverage is reached on at least one of the undercoat bands, the card is cleared and then compared to the vehicle for color match evaluation. This simple task will help the painter choose the proper undercoat shade, realize the number of coats needed for full coverage and evaluate whether the color is a blendable match.Though in the past some painters have often viewed sprayout panels as tools that slow down production, with all the valuable information that can be derived from them, it becomes obvious they can actually increase productivity.
Conclusion
Painting is influenced by many conditions that painters have no control over: humidity, temperature, air movement and the color of the vehicle, just to name a few. Good painters will use all the knowledge, experience and training they have to both control what they can and to minimize problems caused by conditions they cannot control.
Painters who have the ability to mix the correct color precisely to the formula requirements in the exact amount needed — and can also match the color the first time without the need for adjustment or repair — are valuable employees indeed. These painters "measure up" in the mixing room.
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Al ThomasAl Thomas
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