Thursday, 27 May 2010 21:05

Open Clearcoat Blends

Written by  Stefan Gesterkamp
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Although I know better than being surprised about issues that never seem to go away, it still puzzles me how we can hold on to some for as long as we do.

Open clearcoat blends have been attempted and discussed for many years and not once since the departure of lacquer type technology has anybody with technical knowledge decided that they are a really good idea. Granted, from a non-technical, purely financial point of view, they appear worth exploring. Fewer products applied should theoretically lower the cost of the repair, but the reality is quiet the opposite.

Let’s pretend, for the sake of conversation, that an open clearcoat blend within a panel would actually be durable enough to last. Prepping the panel for a successful spot repair is far more involved and labor intensive than a complete refinish of the surface. As a result, it eats up more expenses in labor cost than the additional clearcoat would ever be worth.

Let’s take a closer look into the prep requirement to make this repair happen. After you thoroughly clean the surface and remove any wax or grease, the body tech must repair the damage very carefully. It’s critical to not unnecessarily disturb any paint film surrounding the repair. I know that it is frequently underestimated, but keeping a repair small requires a better trained technician and a higher skill level. It also takes more time to keep it small.

The next step is key for this type of repair to stand a chance of success. It requires the shop to pre-polish the paint surface that you are going to blend your clear over with a heavy duty compound. This is followed of course by another round of surface cleaning.

At this point the paint department would prep and prime the repaired area and, again, spend extra time in the process of keeping it small. After the primer is cured, the surface is being prepped for the paint and blending process. This process requires the painter to step the sanding grid down in size as you get further out into the surrounding surface. The surface preparation also requires the technician to know exactly where his final blend is going to be.

The clearcoat blend has to be over a sanded surface to give it a remote chance of durability, but it must be fine enough to be able to be buffed easily, without burning the edge. A successful paint application for this type of repair also requires a higher skill level on the painter’s part and actually more time to get it done right. The color match has to be closer; there is not much room to really effectively blend out a questionable color. Keeping the surface clean during paint application is also more critical and time consuming. The very thin, solvent-blended clearcoat edge is not giving you much product to work with when it comes to buffing out any particles.

Now, after you have successfully overcome all these hurdles, it is back to polishing the panel for the second time. In all honesty, clients everywhere have expressed to me that it is sometimes hard to get properly paid for color-sand and buff the way it is, what are your chances to get paid twice? If you really take a close look into what it takes to perform an open clear blend within a panel, common sense would dictate that you simply abandon this type of procedure.

The second part of the equation is that most major paint manufacturers will not warranty an open clearcoat blend. The failure rate on this is too high. The more sun exposure a blend edge will get, the faster the deterioration of the edge.

We have all seen the clearcoat blends on sail panels breaking down. Car manufacturers like Toyota and others clearly express their opinions on this subject and require full-panel clear coating on all of their vehicles.

If you start thinking about it, it makes good sense to avoid open blends for more then one reason. Besides the obvious culprits, UV-ray-exposure and chemical fallout, that continuously deteriorate the paint’s surface, do you even know what type of clear is on a vehicle you are trying to repair?

If you are not sure if the clear coated surface of the car is either a pre-flexed, anti scratch, self healing, powder coated or nano technology type clear, then how can you determine the proper technique or product choice?

Different clearcoat technologies have different properties and they may require customized solutions. Let’s just take a look at one of those properties that is unique and directly related to the specific paint technology on the vehicle. It is the expansion and contraction ratio of the paint film itself. This ratio can greatly impact the blends durability.

If the OEM clearcoat expansion and contraction ratio differs during weather related heat-up and cool-down from that of the refinish product, the super thin transition between both coatings will not stand a chance to overcome the ongoing physical stress.

By the way, these differences are not a problem for surfaces that are going to be completely clear coated! And even if you would know the exact expansion and contraction ratios, making this type of repair consistently work for you will be challenging.

Insurers and shops alike say that they want the best possible repair and pre-accident conditions for their clients’ vehicles. If this is the case, then why are we still playing with the idea of sub-standard repairs?

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