You've heard it here before but it bears repeating: the new generation HVLP guns are a vast improvement over the first generation. If you can, borrow one to try from your jobber. Or ask other painters about the guns they've tried. There are a lot of good guns out there now, and the effect they can make on the finish when applying high solids paint is remarkable.High solids paint is thicker, and that alone makes it harder to produce a smooth finish. The temperature of the liquid paint also makes a great difference in the thickness (viscosity) of the paint, and that can greatly affect the way the paint sprays and lays down. Now you can quickly and easily measure the temperature of the paint in the can with the new affordable non-contact thermometers. Checking temperature is as easy as pointing and pressing a button. It's instantaneous, and the thermometer doesn't have to be wiped off.Panel temperature is a second major variable affecting how the paint flows out. With constantly changing weather and air temperatures, how do you get consistency in reaching the sweet spot where the paint flows out smooth but doesn't run? A magnetic panel thermometer can be placed on the rear of the panel, so that you can adjust heat lamps to get the same result every time. An ancillary hand enables you to check later to see the highest temperature reached.A New Concern
For the past few decades, the process was simple: sand until the desired level of flatness was achieved, and then buff to the desired level of gloss. If the primer didn't show, the job was a success.Today, the clear topcoat has to be thick enough to protect the basecoat. Every major automotive manufacturer now specifies that technicians must measure the paint thickness before, during and after any topcoat sanding or buffing is done. The current specification is that no more than a 0.3 to 0.5 mils total decrease in the paint thickness is acceptable. If more topcoat than that is removed, even though the finish may look excellent, it may have to be refinished.One half a mil may not seem like much (it's only about one-tenth the thickness of a piece of paper) but most cars have only 2 to 2.5 mils of clearcoat. Therefore, 0.5 mils is as much as a 25 percent reduction in the clearcoat protection. Refinish paint manufacturers also specify that a minimum of 2 to 2.5 mils of clearcoat must be applied. They further specify that more clearcoat should be applied if the topcoat is to be sanded. A sufficiently thick topcoat is necessary to protect the underlying layers and prevent fading, corrosion and delamination.Thin clearcoat is not just a lofty concern of car manufacturers and paint manufacturers; it can create major problems for refinishers.In a letter to the editor in the August ABRN, Charlie Bright wrote this about his 10 years of experience examining refinish delamination problems: "I've seen nine out of 10 paint technicians skimp on the clearcoat, then polish off 1 to 2 mils religiously." Nobody can see how thick clearcoat is; it has to be checked with an electronic thickness gauge that measures to 0.1 mil. Fortunately, these gauges are now affordable, easy to use and easy to find. They're available through your jobbers and the dealer equipment programs of all major car manufacturers. Although your shop probably doesn't have one now, it should. This gauge cannot only save time and money, it can help you avoid paint problems, too. And any progressive shop can use it very effectively as a sales tool to inform and impress customers as to their level of technology and care.New Small Tools
Every painter has stepped back to admire the beauty of that final topcoat, only to see a little bug, a hair or a black speck which has found its way to the most obvious possible place. Fortunately enamel clearcoats have a window of opportunity where that particle can be plucked out, therefore avoiding having to sand out the imperfection later. Here are some suggestions:* Light spring force tweezers with precision points designed for just this task are available, and they can be easily wiped clean after use.* Nib files are another time-saver for correcting finish defects. One variety is the small wooden block with a piece of a file glued underneath. Here's a trick I found useful: dull the side edges with a Burtex wheel or sandpaper, so they can't scratch surrounding paint during use.* A newer variety of nib file uses a single-edge razor to slice off high spots on runs, drips or other problems. It has a thumbscrew which permits adjustment of how deep the razor cuts, just like the wood planes we used in the shop.When it's time for sanding, there's new help at that stage, too. One flexible sanding block has thin spring steel inside to prevent finger grooves while allowing it to conform to curved surfaces. Plus it has a thumb grip to give greater control during sanding and prevent the block from slipping or falling during wet-sanding. Other sanding blocks are specially shaped to fit the particular styling contours of certain model cars, and still others are ergonomically shaped to improve grip and comfort during sanding.At the final stages of sanding, small solid blocks of abrasive, as fine as 2000 grit, can help flatten nibs. Although these solid blocks wouldn't be good for convex surfaces, in other applications I've found they work amazingly well, and they last just about forever.The Missing Link
In spite of all the new buffers, bonnets, tools, papers and procedures, one vital step was still missing from the process of evaluating and improving paint finishes. Until now, the only means of rating the quality of a finish at a body shop, dealership or car lot has been subjective. Whether a finish was acceptable or whether it matched the other panels has always been an opinion, and everyone has a different opinion.For the first time since paper and polish have been taken to a car's finish, there is an affordable means for shops to measure the quality of the paint's surface finish. This breakthrough was unveiled by DuPont at I-CAR's International Meeting in Pittsburgh, Pa., in August.The instrument measures "Distinctness of Image--Gloss" which is a higher level of perception than a single parameter such as gloss. A brief explanation is that the visual perception of an auto finish involves many things other than gloss. Gloss is defined as the amount of light reflected off a surface. If an orange was chrome plated, it would have excellent gloss, but a person wouldn't rate its finish as being excellent. That's one of the reasons why gloss meters have been unable to successfully discriminate the quality of Class A automotive finishes. The new Quality of Finish Measurement (QFM) instrument designed and made by Pro Motorcar Products Inc. is a small hand-held battery powered instrument which enables measurement and evaluation of automotive finishes. It can be used in the shop or outside at car lots. Drivers Mart Worldwide is already using this to establish the first objective finish standards for both the purchasing and the reconditioning of its cars.This new technology is the missing link which will enable shops to objectively measure the effect on topcoat finish made by changing processes or products in application of paint or in sanding and buffing. It can also be used to more closely match the finish quality of refinished panels to the adjacent OEM finished panels. And finally it permits an individual shop to set measurable finish standards which can be demonstrated to be above the OEM level, or above the competition.
