Today, however, most mold-release agents are a water-based material instead of the wax-based coating used for years. Too much heat melted them flat again.Įxcess heat from sanding also sometimes caused a mold-release problem in the old days. When you returned minutes later, the sand scratches were disappearing. When you walked away from the part, the sand scratches were very evident. Perhaps you’ve seen what happens on certain plastics after a forceful power sanding. Too much power sanding can cause thermoplastics to reflow. Too much sanding can cause problems as well – problems like the “hairing” of TPO bumper covers when the plastic splits and melts into hair-like strands. And more surface area means more places for the new coating to cling to. The surface area to be painted expands by the size of the sand scratches (measure up one scratch, down the next). In my experience, even a light-scuff sanding will help adhesion markedly. Sanding effectively doubles the surface area, thus providing twice the opportunity for the new coating to adhere to the old. While this can be a substantial time saver, I’m an old school guy (not to mention just plain old!) so I’m always happy to have the painter sand the part. Several OEM undercoats don’t have to be sanded under perfect circumstances. As many of your paint reps will tell you, it’s now possible to simply wipe clean and begin spraying on certain OEM parts under certain conditions. Next, let me say that sanding any part prior to refinishing is a good idea. If your dual-action, random-orbit sander is going so fast that it sounds like a jet engine whine, it’s likely that you’ll have problems painting plastics. Plastic parts, however, absorb the heat and can soften or even re-flow under power sanding. Metal parts also get warm as sanding friction heats them up, but metal tends to reflect the heat back out. Sanding friction causes heat, and plastic parts act like a heat sink. Let’s start by talking about sanding plastic components. Whether thermoplastic or thermoset, today’s parts can be treated uniformly. I’m pleased to report that to successfully paint plastic automobile parts today, it’s no longer necessary to name the plastic first. Some identification tests included floating a chunk of the unknown material in water. Over time, painters were expected to burn a sliver of the mystery plastic and name it based on the color of the flame or the smell of the smoke. When the identifier was missing, other methods of identification were necessary. And auto painters have suffered through a lot of grief trying to identify the type of plastic based on a two- or three-letter identifier stamped (seldom) on the back of the part. I will keep this group posted on the updates and meanwhile, other BHPians who have this issue, I would advise you to please write to KIA care on the same with pics, or get the car inspected with your respective service centers.It’s been a long road from the first flexible bumper cover on the 1967 Pontiac GTO to the latest body cladding on the 2004 Pontiac Aztec. I did share my concern on the fit and finish from the showroom after the paint job and also if the issue will reoccur even after the painting, the SA promised me that they have done many white bumper paintings, and even after one year there is no difference, so l would have to go by their word and try to get this fixed. But since still there are LD restrictions in Kerala, they have told me that they will find a suitable time in the next 2 weeks and inform me so that they can do the painting and they promised me the car in 3 days. Anyways, they have acknowledged the issue and agreed that there is discoloration and this would be fixed as part of the warranty. As per the SA, this issue is happening in pearl white color and ideally, in the factory, there should be a slight difference in the paint mix for the bumper and metal, but looks like KIA uses the same mix for both, hence this issue (I am really not sure if this issue happened only with the initial batches of Seltos's or it is still happening for the newer lot). I visited Incheon KIA this Monday and the initial impressions were really good, the SA and the paint shop manager seemed to be genuinely concerned about the issue. At this moment there was an LD in Kerala, hence he assured me that he will contact me as soon as the LD is lifted, and as promised he contacted me and scheduled an inspection. KIA responded immediately and asked me about my current location, I said it's Cochin and the dealer is Incheon KIA, so they have looped in Incheon into the communication and I immediately got a call from the customer relationship manager. I wrote a mail to KIA, attaching the pic with all the relevant details. This discoloration has been bothering me a lot, typical OCD of BHP'ians.
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