Let's answer Token first. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> Generally the decals used in applications where paint is applied over them is not the traditional stick-on type that you have made at your nearest vinyl shop. I have quite a bit of experience in spray-painting, and the fact is that, ?till very recently the practice was to use water transfer decals if you wanted to paint over them. However, having said that, I can only speak from my own experience, which is limited to one or two occasions over the last 17 years, so I am very happy to accept from Mampara's and your own experience that it is possible to paint over stick on decals if they are of the right type, and you have time, and you know what you are doing. As I said, I will actually give it a go at some point, as my airbrush and stencil skills are non-existent. As I have now had the time to count to ten, let me turn my attention to to Johan (and my sincerest apologies to all for the thread hijack here!): You don't really like to hear that not everyone agrees with you heh? Just for the record of other hubbers that may be reading here, may I point out that your snide remark towards "rocket scientists" in a previous thread (chain stretching) was directly aimed at me, even though I didn?t even take part in that particular discussion. This back-handed swipe followed from a private disagreement we had regarding the basic laws of physics. I especially considered the "rocket scientist" remark as a bit of a low blow, as I at least had the decency and ethics to significantly differ from you in private. I believed then, as I do now, that you add a lot of value here, and I agree with most everything you say. For this reason I didn't want to detract from the good that you do, by picking at a perceived gap in your understanding, nor by responding publicly in any way to your underhanded tactics. Not that I originally mailed you and called you an idiot - I think my mail was sent in a well mannered and good natured way. Then too you got all curt and snotty the moment someone dared to differ from you and your last private mail, sighting lack of time for arguments, proved that you simply hate being wrong. I guess it isn't always easy for us humans to come to grips with the fact that we sometimes get answers wrong. I do however hope my response in this thread to Token and Mampara's challenges to my understanding has then at least proven that you and I differ in this one crucial way: I accept that others may know more stuff than I do, and will publicly admit to that. You don?t and won?t. Having gotten that off my chest then, here follows paint chemistry 101 (backed up by my good friends at Advanced Material Technologies, Glasurit and Plascon, who again know more than I do): Automotive paints are generally epoxy based two part concoctions these days, typically consisting of 50% paint, 50% hardener or catalyst, and an optional small quantity of a volatile component or thinner. (This volatile component is -and I really don't know if the spelling is correct- a chemical called polyacrisane.) The volatile component content is very low, and hence flashover times extremely short. This is because modern HVLP equipment allows for very fine atomization, hence a smooth enough application that extended flow time is no longer a prerequisite for a glossy finish. Full hardening after flashover is actually a function of a chemical reaction between the catalyst and the epoxy based paint, and not of the evaporation of the solvent. Traditional solvent based paints (like the stuff in rattle cans), usually contain very high levels of solvents ? it can be as high as 50% by volume. This is because hardening is purely a function of the rate at which these evaporate from the paint, and if you add too little volatile contents, you get a bad surface finish, as the paint does not have enough time to flow before it hardens. In order to provide for a smooth finish, you will also find that the solvents do not evaporate off at a very fast rate (longer flashover times), allowing for the paint to "flow". Due to this, there is also a longer period for the solvents to react with whatever the base is onto which the paint is applied. This is not a problem in itself, except that in the case non-epoxy paints (such as rattle cans), the solvent has an acetone base, and as you may know, acetone is one of only a few compounds that removes epoxy (fibreglass/carbon fibre resin) from anything. Pure acetone itself is no longer used, as it is carcinogenic, but the stuff used has exactly the same solvent properties. So then the answer to your challenges: "What are those nasty solvents and how do they differ from automotive solvents?" Acetone-based solvents. Fact is that automotive based solvents as used with epoxies contain nothing that even remotely behaves like acetone, or traditional thinners. The solvent in automotive paints is polyacrisane, and that in rattle cans or ?laquer paints? (including Duco, QD enamel etc.) is a variant of acetone. Polyacrisane does not attack the polymer chains in resin, acetone eats it for breakfast. "What makes you think your inert automotive solvents were used in the first place." Because Truvative are known for the vast quantities of clearcoat rattlecans they buy. Not? Oh, I guess then it is safe to assume that they use proper modern production techniques which will see them use an epoxy based paint system. Not only from a common sense perspective, but perhaps also from the fact that their local environmental agency will definitely be very happy if they were to use acetone based solvents in large quantities! It might of course be that they didn't even paint the components, because if moulds are of high quality the final product will be perfect in any case, and won?t need any paint? Speaking of environmental agencies; the latest trend is for automotive paints to be water based, and not to be sprayed on with compressed air, but rather splattered on using nozzles that rotate at high speeds, so as to further reduce pollution. "Explain how a spayed on layer will affect the structural integrity." Because the acetone based solvents in the paint will penetrate the structural component, and structural integrity is based on how far a solvent will penetrate the composite before it has had enough time to evaporate. OK, so I don't know by how much it will penetrate. It might be 0.1mm, it might be 0.2mm. Hell it might even be 1cm. The fact is that I don't know how far exactly, and neither do you. If you want to wear your pseudo scientific hat, then I suggest we ignore it completely. So let?s tell people to go buy a rattle can, and risk ing op some poor hubber's cycling components all for the sake of your fragile ego.
