![]() Moving to water borne is expensive and tricky. So sold VOC compliant but not really in practice, and everyone looks the other way because they don't really generate enough pollution to be worth cracking down. So the real result is that the coatings are made higher solids and then get reduced by the user with a significant amount of VOC (toluene, NBA) so they are usable again. Of course, acetone flashes off way too quickly, making it almost impossible to get coatings to level and flow properly. They used to use, mostly (but it varies a bit), n-butyl acetate. It is the main carrier in almost all solvent borne VOC compliant formulations of coatingsĪs a result, for example, roughly all solvent borne wood coatings that are VOC compliant use acetone these days. Since the definition here is the regulatory one, it is not a VOC as we're talking about. Scientifically, yes, but it is exempt from almost all regulation as a VOC. One of the innovations of the Dodge Brothers (that Ford later copied) was that by using more metal body components, not only do you save on labor (working with wood is much more skilled than running a metal press) but that metal can withstand the much faster oven-baked finishes. And they were more durable because they produced a more flexible coat. So paint could just be poured on and the surface tension would smooth the surface perfectly. You could get thicker coats that dried faster. This was still pretty new technology then and the precursor to our modern petrochemical derived paints and even plastics. At final assembly they will all be matched up together without any mismatching paint jobs.Īnd we cannot understate how magical the introduction of asphaltum and naptha were to the paints. Part of the magic of the all-black Model T is that you can just dip parts that can be dipped, Japan parts that can be Japanned, and pour paint on parts that cannot. In addition to time, this is a huge QC issue. And to get that nice shiny enamel surface we are used to with hand brushes, they had to alternate the direction of the brushstrokes between every coat as well as sand it. There's so much more detail you can go into in this stuff.īefore the Model T assembly line in 1916, most manufacturers did something like 6 or 7 coats by hand because it was such thin, slow drying varnish. "Why did this vehicle go here" is not a straightforward question to answer sometimes. Then either IT or OT (operational technology) can make a routing decision, or an individual can use a key switch to manually change routing. The electronic quality and build data has to be synchronized with the physical process, and that data package can be updated by several different systems. Paint shops have the most complicating routing of any part of automotive assembly. If too much of the oil has evaporated, then you start getting corrosion, and in many cases you won't be able to tell until the vehicle gets to the customer. The metal panels have oil on them in stamping, and they MUST stay oiled right up to the point where the body takes it's first bath. The body is just dumb metal, right? Of course not. Someone did weekend work on the roof? Congratulations on your dust quality spill (spill means a bunch of problems).Īll of the parts of the paint have to work together, and that includes things that you don't think are paint. Livestrong bracelets also ruined at least a hundred paint jobs. Someone in IT applied some lubricant to a label printer and ruined hundreds of paint jobs. Our solvent paint process (pre-2013) was very vulnerable to siloxane (silicone) lubricants. Temperature and humidity (dew point) are the biggest besides the actual paint mix, but there's also unexpected problems from every direction. Paint is the hardest thing to get right in the whole assembly process, because there are so many process variables. That is only certified reliable with less than 5 trips through the ovens (in my shop). They have to stick to the paint, and the paint has to stick to the body. Windshields are glued in with specialized urethane 'caulking'. The main limit on repairs though? The windshield. For the shop I worked in, we got 2 tries to repair. ![]() All of those things don't really love being baked too long. Some panels are filled with foam there's internal sealant and glue, and external sealant. ![]() The trips through the oven affect more than just the paint. There's a limit on the number of tries you have to "repair" the paint job, because the vehicle has to go through the oven again to bake the coatings. I used to work in an automotive paint shop. ![]()
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