Richard Read
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Thanks, I had been thinking about a DIY approach similar to what you have suggested.
I said to my mate that it was a nightmare and I’d pay towards a body shop doing them, but so far none of the ones he has contacted are willing. He has offered to help with the prep so maybe I’ll have to try and get some dowel…
I see now. Well Mipa do a 2k transparant sealer that will adhere to bare alloy and is non-sanding / wet-on-wet. I have not used it, but heard it’s good.
http://mipa.de/gb/product/prodinfo/produkt331.html
It does recommend to use a dedicated primer for best corrosion protection, though I guess it depends on what kind of warranty you want to offer. It is probably fine for small areas and a lifetime of a few years. Given your short time allowance for the job, maybe it is just as effective as what you do now, as if you prime over etch without a leaving a good while the acid can prevent full adhesion/cure of the primer.
An etch or epoxy won’t really stop existing corrosion, you need to remove it by sanding or grinding then build the area back up with filler. What is the MaxMeyer primer you are using? Some primers are not meant for direct to alloy.
You say you want to stay with wet on wet, but you want more build. Surely that is going to give you mapping issues? If you get more build you will need to feather the edges. Maybe best to stick with a wet on wet primer with low build and just get your prep right.
Not all primers can be thinned down to use as a sealer – check the data sheet.
I imagine you can get Mipa products easily in Holland as you are nearer Germany? They do a transparant sealer which is good.
I’m in Gloucester.
Thanks for your reply. It’s extremely rare that I’ll do a full paint, mostly panels. I also design, build and paint high end loudspeaker cabinets. I thought the speed of the clear was down to the hardener? And to an extent the thinners. I thought faster products were not as good in terms of durability, gloss, lifetime etc. I’m not a colission shop working to a time schedule, I’m preferring to lean towards quality.
I’m using solvent basecoat.
I don’t have a booth, just a garage with good sealing and insulation and dehumidifier. It’s quite common over here in England to spray 1k products as 2k is mandated to use an air fed mask, which not a lot of people have. The sizes of compressors you guys have in your garages is unbelievable! They are so cheap over there.
It’s good that you mention about UV protection and gloss retention. These are factors I’m interested in.
Hi there.
You would think that the primer should “shield” any texture or whatever it is on the substrate from being a problem.
Blasting is supposed to provide the best surface for adhesion. I don’t think the heat will really do anything though, it would speed up the cure of the epoxy, but the top coats wouldn’t be hugely affected because it’s a single pack product.
The base and clear you already use should be fine over the epoxy primer. If you leave the epoxy longer than about 5 days you will need to key it up. It’s best to paint over it within a couple of days as the cross linking is still going on so it bonds better to the colour coat.
I said I’d redo them after winter as I wanted to clear over them. What would your recommendation be regarding using my electric 125mm DA, or my mini 50mm air DA, or hand? I’m kind of leaning towards the mini DA as I can get around the bulge and generally it’s easier to control? I’m working with the lights on the car. I never thought that a machined grit would work differently to the same grit by hand.
One comment, I know the US grits are different to European P rated grits so it can be confusing.
Thanks for the replies. Andy, the ones I did were at least as bad as that. I did all the sanding by hand and tried to sand up and down then left and right – but on each grit rather than alternating (is that bad?). Reading what you said in that thread, I started too coarse for hand sanding. I didn’t want to DA them as they have a bulge in the top like a frogs head, and I wanted to wet sand them. My DA sander is electric.
I guess the issue now is how to remove the P220 scratches? I did work quite hard with P400, is skipping one grade really going to make that much difference? I do have a mini (2 inch) air DA sander – if I could get a foam backed velcro pad for this maybe I could tackle the bulge?
edit: something like this but with the screw thread to suit my tool [url=http://www.powertoolsdirect.com/flexipads-spindle-pad-50mm-conical-soft-face-velcro]foam backing pad[/url]
You forgot to say that you are in Germany 😉
Epoxy primer will help with the chipping. Mipa is a German paint company and they do an epoxy primer. Using 2k topcoats will help further, but then you need breathing apparatus and consideration of those also around where your workshop is, as the fumes can bring on severe and lasting issues.
HB Body Bumpersoft filler should be suitable as it’s designed for bumpers made of pur, pp etc.
Yes there is definitely a pressure loss so you really should be using a gun gauge. I see about 4 PSI loss through 3 metres of 10mm hose with high flow fittings.