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Tag Archives: paint defects

Color matching problems not related to the paint itself

Probably color-matching problems are among the most frequent paint defects in the car refinishing industry. It is also the main cause of expensive re-works and unhappy customers. In many cases, the poor color-matching is due to the darker or lighter appearance of the final result. Below I bring to your attention 6 parameters a painter should consider before the basecoat application:

Spray gun pressure

Unfortunately, many painters underestimate the importance of precise measurement of the spray gun inlet pressure. They either do not use a manometer at all, or rely on a poor quality analog manometer.

Outcome: Lower than designated pressure causes darker color result, while higher pressure – lighter color than needed.

Solution: Use a reliable manometer, preferably digital one, for each basecoat application job.

Humidity

Most of the paint manufacturers state the ideal humidity level for the perfect applications conditions. However, we do not have the possibility to control humidity levels easily. For your reference, ideal humidity level is between 30% and 50%, lower than 30% humidity is considered low, while higher than 50% humidity is considered high.

Outcome: Low humidity causes darker result, while high humidity – lighter result

Solution: Adjust viscosity based on the instructions from paint manufacturer, consider changing nozzle size and air cap with lower or higher air flow (consider switching between higher air volume HVLP technology gun and lower volume Devilbiss Trans-Tech or High Efficiency or SATA RP).

Temperature

Just like with humidity, every manufacturer advises the optimal temperature levels for the application. Unlike humidity, it is easier to adjust temperature levels in a workshop, but still there are limitations as well. As a rule of thumb, low temperatures can be considered the range from 15 to 20° C, normal – 20-25° C and high – 28-35° C

Outcome: Lower temperatures will cause darker results, while higher temperatures – lighter results.

Solution: Adjust viscosity based on the instructions from paint manufacturer, consider changing nozzle size and air cap with lower or higher air flow (consider switching between higher air volume HVLP technology gun and lower volume Devilbiss Trans-Tech or High Efficiency or SATA RP).

Thinning (dilution)

Every single automotive coating product comes with a detailed technical data sheet. Unfortunately, often painters either ignore those data sheets or simply continue to work with any new product the “good old way”. In reality, under thinning or over thinning will inevitably cause color problems.

Outcome: Under thinning will cause darker color shade, while over thinning will produce lighter than needed variation.

Solution: Follow the manufacturers’ technical instructions, labels and manuals. Use mixing cups with measurement marking, scales and mixing rulers.

Spray gun distance from the surface

Every sprayer has its own style and spraying technique, however certain standards must be respected. One of the parameters I refer to is a distance between the spay gun and the vehicle’s surface. Consider that normal distance lies within 15 to 25cm range.

Outcome: Too small distance will cause darker colors, too high distance – lighter variation.

Solution: Respect the advised distance between the gun and the surface.

Speed of spraying

Similarly, speed of paint application is very individual and varies from sprayer to sprayer. However, extremes are not good.

Outcome: Spraying with too low speed will cause darker colors, while spraying at excessive speed – lighter color than expected.

Solution: Follow the paint and spray gun manufacturers’ instructions.

 

The best polishing compound for a bodyshop is… 12 steps guide to find one for yourself.

etalon refinish

Probably when you think of car refinishing job, paint polishing is not the first thing to come up in your mind. Nevertheless, it is an important process for any collision repair specialist. Firstly, when a minor paint defect occurs, in 9  cases out of 10, you will need a compound and a polisher to fix the problem. Secondly, a full car detailing could and should be an additional service offered to a customer who walked through your shop’s door.

Consumption of a polishing compound varies from one shop to another. Usually the excessive use of a compound means two things: too many paint defects revealed during the inspection process or/and incorrect polishing process. I have seen an operator pouring a quarter of a bottle to polish a fender. Also, in certain markets with poor working conditions without a proper spraying equipment, painters have to wet-sand all the repaired surfaces to remove orange peel and numerous dust nibs. It comes with no surprise that in these cases polishing compounds’ and glazes’ consumption is sky-high. What I would like to share with you in this article though is a short guide how to pick up the right polish for you. This is not the advertisement for Etalon polishing system, and my tips come from my own experience and the extensive knowledge of my colleagues and employees.

 

  1. Examine the surface to be polished. Before you decide which compound to use (yes, it’s good to have a few compounds to choose from), you need to understand the condition of paint or clearcoat you will work on. In a bodyshop usually we use compound to remove paint defects, meaning that paint is fresh. Is is crucial to know if the clear was properly baked in accordance with the manufacturers technical data sheet. If you choose too aggressive compound on still soft clear, big chances are that you will end up with excessive haze and swirls. It has nothing to do with the quality of the compound, but with the clearcoat’s chemistry instead.

 

  1. Check what polishing pads do you have available. The quality of paint rectification depends on many factors, like the polish machine, compound used, pads the compound is applied with and, an operator’s skills,indeed. So, if you do not have a quality wool pad handy, then you may need to go for more aggressive polishing compound. While if you have only rotary polisher in your tool box (read the article about polishing machines here), then a choice of medium cut compound would be a reasonable choice for safe polishing.

 

  1. Check what abrasives you have at your disposal. Nowadays one can find in a body and paint supply shop a great assortment of micro abrasive products. It is not necessary any more to remove orange peel, for example, with a polishing compound only. If you choose a film based abrasive disc P1500 first, then rectify the surface with P2000 or P2500, the entire process will take 3 times faster than a compound only process.

 

  1. Assess the ambiance and surface temperature. In case you have high temperatures in your workshop, choose a liquid polishing compound (not a paste) with oily consistency. There are polishing compounds in the market which turn to dust within first minute of use. This occurs due the high solvent content in them. These solvents evaporate very quickly when temperatures are high. You will have to add more and more compound to keep working and face an unpleasant dust spreading around.

 

  1. Avoid compounds, which require added water. You can still find the products in the market, which require adding certain quantity of water before and during the work. It will create a lot of splashes and unnecessary cleaning afterwards.

 

  1. Avoid difficult to clean compounds. I have seen otherwise good products, which are very difficult to wipe off especially from rubber and plastic parts. Such polishes will either require meticulous masking job prior polishing or long time spent on cleaning the residues. No, thanks.

 

  1. Choose a polishing compound with the best cut/gloss ratio. The times when cutting compound was leaving almost mat surface are gone for good. As a matter of fact, you can find fairly cutting compounds which leave lustrous surface with a very high gloss level. Certain brands market such products as one-step. However, you should remember that on the dark colors you may still need a finish glaze with anti-hologram properties.

 

  1. Avoid polishing compounds with silicone. Check that a bottle has a “silicone free” or “bodyshop safe” tag on it. No need to explain why.

 

  1. Avoid polishing compounds with waxes or sealants. It is very popular amongst car detailers to use so called “two-in-one” polishes, which combine abrasive and waxing properties. In a bodyshop, however, the clearcoat, albeit properly dried, still “breathe” with solvents. We don’t want to seal the pores of the paint, while solvent is still making its way out. Generally it is advised not to apply any waxes or sealants within two weeks from the paint job to avoid dieback of the clear coat.

 

  1. Prefer a polishing system with only a few polishing products available. Some brands offer just one-product system, but from real life experience it is obvious that there is still no perfect single compound for all jobs. Likewise, do not be misled by systems with far too many products.

 

  1. Avoid compounds with fillers inside. In car care and cosmetics market you may see a great variety of the polishes with filling properties. Such a product doesn’t remove scratches, but rather mask them for a limited period of time (usually until the next proper wash). The last thing a professional car sprayer needs is the angry customer coming to the shop and spotting the places where a paint defect was. A real pro will remove the paint defect, not mask it.

 

  1. Do not choose the polishing system just because it’s cheap. The cost of polishing materials in the overall bodyshop repair bill is negligible, but the spent on compound might be too long to afford.

 

Bonus tip. If you want to compare to compounds, do it exactly under the same conditions; for instance, split a bonnet half by half and do your test with the same polisher, same pressure, time and pad type. Do not mix two compounds on one pad in order to avoid misleading results.

 

 

 

 

The best polishing machine for a collision repair shop is …

 

To make it clear from the beginning, I will not name the best brand or model, even if I do have a very strong opinion about the best electric tools in the market. The main objective of this short post is to clarify to our readers what machine they should have in their bodyshop to solve car refinishing problems. For the last couple of years, collision repair professionals have been approached with a great variety of tools, and I have been asked quite a few times about the best choice.

Types of polishing machines

All the existing polishing machines in the market can be divided into three categories: rotary, random orbital and dual action (DA). Below I am going to explain the major differences between them.

Rotary polishers

Rotary polishers are the oldest polishing tools in the market. They use simple circular motion on a single axis. Modern rotary polishers come in a variety of designs and with the possibility of speed adjustment (usually from 600 to 2500 rpm), but the two most important parameters we check in a rotary machine is the power output and weight.

Orbital polishers

Orbital polishers unlike the rotary polishers, which are using direct drive on one axis, have two centers – machine central spindle and pad’s own axis. The movement of the pad is orbital, like the Earth’s movement around the Sun. The shape of the orbit depends on the distance between the two axes. This distance is a crucial technical parameter and usually is somewhere between 8 to 21mm. The best example (at least from marketing point of view) of random orbital technology is Rupes Big Foot series. The good thing about orbital polishers is that they are very safe, and it is almost impossible to overheat or damage the coating while using an orbital polisher.

Dual action polishers

Dual action or DA polishers are usually confused with orbital ones. DAs are actually a hybrid between rotary and orbital machine, in which forced rotary movement is combined with orbital. This machine is supposed to have the best from the two worlds. Flex XC3401 VRG is the most known DA polisher in the market. The Das indeed can do the job of minor scratches correction, on the other hands, it is very hard to remove wet sanding marks, for example.

What polisher shall we buy for a bodyshop and why?

First of all, we need to understand when usually we use a polishing machine in the collision repair shop? The main usage of polishing or buffing in a bodyshop occurs when a painter needs to remove certain paint defects revealed after the repair job is completed. The most frequent paint defects, which require buffing, are dust nibs, runs, excessive orange peel and clearcoat dieback. Usually prior to compounding, a painter use either wet or dry sanding paper to speed up the polishing process altogether. So, in other words, polisher is a kind of fire extinguisher helping to prevent the potential customer’s complaints. Nobody likes those nasty dust nibs on a freshly painted car. The key parameter for polishing is the speed. Paint defects must be removed quickly and effectively, so that the vehicle could leave the workshop on time.

From the three types of polishers I mentioned above, the fastest and the most powerful tool is a rotary buffer. Rotary machine quickly increases the temperature of the paint, softens it and by friction between pad, compound and the surface, removes the upper layer of the clearcoat. DA polisher and especially random orbital machines will fail in most of the instances to remove sand paper scratches even from grit P2000. Fact. Despite the ease of use and safety, dual action and orbital polishers are not the preferred tools for a bodyshop professional. They are very useful for the detailers to remove holograms, swirls and to apply wax or sealant, but this is another job.

Conclusion

If you need to buy a polishing machine (every bodyshop must have one), go for a reliable rotary polisher. Pay attention to the machine’s weight (something within 2-2.5kg range is a good choice) and power output (900 – 1100 Watt are good enough). However, if you consider to offer polishing and detailing services, which I strongly recommend you to do (read a separate article about this topic here), then a DA polisher or random orbital one will be a well-justified and worthwhile investment.

 

P.S. A car sprayer should consider purchasing a pneumatic orbital polishing machine. Unlike car detailing shops, all bodyshops are equipped with decent air compressors. Pneumatic polishers are powerful, durable, lightweight and almost maintenance free.

Etalon infographics series. Foam vs wool pads.

Foam vs wool pads

4 important steps for bumper refinishing job

By nature, bumpers are designed to protect a vehicle, so it is the most common part of the car to be repaired. In fact, all statistics prove that. However, we see many mistakes done during the process of the preparation of the bumper for the paint job. Below I present 4 easy, but very important steps to have smooth and high quality repair job on a plastic bumper.

  1. Clean, clean and clean

etalon-5

Whether it is an old bumper or a new unpainted spare bumper from OEM, meticulous cleaning is necessary. Old bumper may contain all sorts of contaminations, including dust, dirt, oils and polishing compounds. New part may have remains of the molding waxes and dust. Do not skip this important step. The best way is to apply the cleaner/degreaser by special pressure sprayer and to use two wipes. Use the first wipe to lift the dirt from the surface and second wipe to dry out the surface thoroughly.

  1. Scuff properly all the surface of the bumper

Glossy bumper 1                                  Glossy bumper 2

Probably you have seen many times vehicles with paint pilled off. One of the reasons is that old paint on the bumper was not properly sanded to create appropriate surface for the new coating’s adhesion. On the below pictures you could see some spots where old paint was poorly scuffed. Use nonwoven sanding pad, soft abrasive pad or sand with random orbital sander with a soft intermediate pad for better results. Inspect carefully the surface for untreated spots.

  1. Use special putty/filler for the plastic parts

Putty for plastics

We have to keep in mind that the materials common bumpers are made of nowadays have been changed from metal and rigid plastics to softer thermoplastics. Consequently, new types of bumpers are subject to shrinkage and expansion much more than the previously used materials. Normal polyester filler is simply not flexible enough. Make sure that you use a polyester filler, which can pass the “tube test”. This is a very easy test you can perform in your bodyshop. Apply a thick layer (up to 1mm), 10cm wide and 20cm long from a plastic putty on backside of waterproof sanding paper sheet. Let it dry for about 10 minutes. Hand sand it as per manufacturer’s instructions or with grit P180. Then, try to roll the dried film of the putty in a tube (see the picture below). If it cracks, then it is not flexible enough. Unfortunately, there are many polyester putties on the market, which have no difference with the common putties, but the colour (usually black or dark grey).

Flexibility is the key

  1. Always use plastic adhesion promoter

We have noticed that even some of experienced painters avoid using plastic primer/sealer prior application of filling primer and paint. However, skipping this important step is yet another reason why we see so many cars with pilled off paint on the roads. Spray a light coat of the plastic primer on the spots with unpainted or exposed plastic. In case of a new unprimed bumper, spray the whole surface. Usually adhesion promoter is transparent, available for spray gun or in aerosol can. For example, Etalon plastic primer includes also light metallic particles so that it would be visible where the primer was already applied. Wait for about 15 minutes prior applying filling primer.

Spots to apply plastic primer

Have also a look on our previous article: “Why metallic colours look different on car’s metal and plastic parts like bumpers and spoilers?”

 

 

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