Bug splats and waterbased paint don't mix
This car belongs to a great chap called Tony, he has become a regular and very good customer of mine. Tony is a very active member of a worldwide BMW forum, www.e90post.com. I first detailed this lovely 335i Coupe during the summer, Tony making the trip from central London to my house for the day, for what turned out to be very long detail finishing somewhere near mid-night.
The main issue was the front bumper, covered in bug splats. Tony’s a regular visitor to Europe so doing plenty of motorway miles and just like me is a confirmed Nurburgring junkie. During that first detail I tried everything to remove the remnants of the impacts – clay, solvents, heat, abrasive compounds. Nothing would touch them, and mostly they couldn’t be felt. Like etching from a bird bomb, they had chemically etched into the clearcoat so the only way to rectify it was to wetsand the whole bumper. It was a long and laborious job but got it done – hence the late finish that night.
Now fast forward a couple of months, Tony was taking his forum members on a guided trip to the Ring, and just after was due to have his car featured in a magazine thanks to some of the under bonnet tuning it has received. So, I went to visit him at home to give the car a tidy up. Much to both our disappointments, the bug splats were back all over the bumper, and this time the bonnet had a lot as well. A good wash acted exactly as before – all the solid debris came away easily from the well waxed surface (I applied 2 layer of Swissvax Best of Show, Tony had added to it since), but the echo’s of their fate were firmly etched in, including some trails left by particularly juicy entrails right up the bonnet. I figured there must be something really wrong here, and urged Tony to speak to his bodyshop and ask their advice.
The bodyshop said this is something they have seen an increasing amount in the last 12 months, the waterbased paints simply not offering the same sort of resistance to this sort of thing as solvent based paints did. Their suggestion was to wetsand the bonnet to remove the bugs, then polish it up. They also believe that the polishing stage will act to further harden the paint. I can’t comment on, or explain, the science behind that statement, but it seemed like the only way forward avoiding a respray.
So, with the task ahead I phoned another good friend of mine and fellow Detailer, Bryan, and asked if he would help me. I’ve done quite a lot of localised wetsanding to remove specific problems but not complete panels in one go. Knowing the time it would take, and the importance of refinishing the paint correctly (where two sets of skilled eyes are always better than one) I asked for his assistance and he very kindly agreed. His unit was the ideal location so the date was set.
Come the day, the Tony managed to arrive 3 hours later after he overslept, then got a puncture on the way down. We forgave him though, it was his 30th birthday! Undeterred, we cracked on straight away to get the car clean, using Bryan’s newly bought foam lance to keep him happy ;)
As a slight aside, this was also my first chance to use a natural sea sponge to wash the car, something that is popular amongst some members of the Detailing community – the Shine On verdict? Thumbs down. While I appreciate what is said about it effectively releasing all the dirt it collects, it didn’t feel at all like it moved smoothly across the paint, and I still can’t see it has anywhere to put the dirt other than directly between itself and the paint. So I’ll stick to my lambswool mitts for washing.
Dried off and into the unit, Bryan removed the front number plate and masked appropriate area’s while I took lots of paint thickness readings. The ultrasonic Positector gauge really came into it’s own here, giving a good split reading of the layers of paint and showing around 45 micron’s of clearcoat over the affected areas. We also noted the front edge of the roof needed attention, and a bird bomb mark on the boot lid while we were at it.
The bugs at large:
With a sanding block each, we took a sheet of 3000 Unigrit from the bucket of soapy warm water they had been soaking in and started to sand the bonnet. Working in small area’s at a time, constantly keeping the area well lubricated, we kept checking our work and re-measuring how much clear was being removed. While it looked savage, it was actually barely touching it, so we upped our assault to 2500 grit paper.
The customer looked on, giggling nervously…..
Not really surprising, seeing as this is what he was looking at
Having removed on average 3-4 microns to remove the damage, we worked our way up the bonnet, switching back to 3000 for the less affected areas. The front bumper was treated in the same manner, as were the wings down to the swage line. The fronts needed sanding anyway, the rest was done to blend in the now much reduced orange peel effect on the bonnet, it might have looked odd otherwise. There were a few particularly obvious stone chips for which Bryan miraculously had the correct colour touch in stick, so he dobbed some paint into them. As the Tony was taking the car for a full frontal paintshield (plastic film) treatment the next day, we thought this would be the best time.
Poor Tony still looked on with a ‘What have you done?’ look on his face….
To make polishing easier, we used a randon orbit dual action machine fitted with a 4000 grit sanding disc to go over the whole bonnet, wings and bumper. Most people have never come across sandpaper this fine, running your fingertips across it it certainly doesn’t feel like an abrasive paper.
The sanding complete, we took the chance to make a coffee and take stock of the job so far.
Re-energised, it was time to start making good again. Bryan grabbed a spot pad and started polishing the bumper, I went for a 6.5” Megs polishing pad and got on with the bonnet, both using an aggressive 3M polishing compound needed to remove the sanding marks. Like the sanding itself, this isn’t a stage to be rushed. Polishing is like a super-fine method of sanding, and needs to be done gradually and with care. By having used the 4000 grit paper last it meant that the sanding marks were as fine and uniform as possible, making the polishing stage a little easier. Below, you can see the first area polished, the hard paint responding well to the compound being used.
Once we had done an initial hit everywhere with the compound, we gave the paintwork a wipe down with an alcohol solution to remove any hint of filling oils from the polish and clearly show exactly what needed to be done. We then used a fine finishing polish to refine the paint and restore the maximum gloss. In a few places that needed further work we used a medium cut polish for it’s extra bite.
This had taken a good few hours, nearly 8 in fact, a couple of pizza’s and a host of coffee’s. But, we got there in the end and it looked fabulous. We gave the areas to be covered in film a light spritz of a paint sealant, just to give some protection from the elements on the way to the paint film fitters the next day, and I topped up the wax on the rest of the car using Swissvax Best of Show. The pictures don’t really do justice to the amazing deep finish the paint was left with.
It was an enjoyable day, we all had a giggle, and Tony’s car was once again restored to its former glory.
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