Game of 'Spot the Difference' anyone?
The past six weeks have been a nightmare, after being in the garage for a few days in the warm micro blisters started appearing on the chassis -
Paint supplier believes it to be caused by damp in the primer so they are moisture blisters rather than solvent pop.
I spent some time flatting them back and polishing them out but within 24 hours more where appearing at a good rate, strange as the paint had been applied a few weeks earlier but now the reaction was speeding up.
So I made the daunting decision to take all the paint off back to bare metal and start again, this is a significant task as there are many hard to access areas on the chassis so it took a few days to get all the paint off.
Next decision was what to do about paint as I have never experienced this before. I took the following approach to prevent it happening again -
1. Dry sanding of primer only, I am a bit old school and still wet sand primer as its easier with less risk of scratching the surface.
2. Control the humidity level. Average external humidity level here is 86% so anything less than that is a bonus. I painted the chassis in June which you would expect to be ok but the weather was awful. Looking back at my weather station records on the 14th when I painted the chassis the humidity was 92%. I didn't think to run my de-humidifier so this time I will run it overnight and aim for a 60% internal humidity level.
3. Control the temperature, use my IR panel heater to bring the temperature in the garage up to an acceptable level.
4. Strict control of mixing volumes and flash off times to make sure it isn't solvent pop after all.
5. Make sure my three airline filters are in good order, I run an initial filter at the compressor, then an internal 3 stage filter plus an inline filter.
6. Use a fresh batch of paint just in case.
So after a week of priming, sanding and prepping I was good to go. Waited for a good dry day, made absolutely sure the primer was dry and cured then sprayed the 2K acrylic black. Went on great and looked superb so I left the panel heater on over night to help curing and went to bed.
Next morning I went to the garage to have a look and guess what, micro blisters everywhere WTF!!
I am totally baffled, the problem hasn't appeared on any other parts that I have sprayed with the same paint and processes. Neither have I experienced anything like it in over 40 years of painting, I think I can only blame the weather and global warming.
So where to go from there? I had to dig deep and start again stripping back to bare metal, I tell you I was gutted. No point in taking a chance and using the same paint again so I decided to go with Corroless RF16 and to give me something different to aim for and break the monotony of it all a bit go with a mid-grey colour.
So again after a week of preparation and only using Corroless S1 primer this time following the manufacturers recommendation exactly I sprayed the top colour coat. This is the first time I have sprayed RF16 and I must say I am very impressed, goes on very nicely and flows out great without any tendency to sag at all. Its perhaps what I should have used in the first place as it is designed for this purpose.
Next morning it had dried rock hard and looked great so at last I am almost back to where I was 6 weeks ago
Never mind, good news is that my new engine is due this week so I am going to start gearing up to get the gearbox and engine fitted.
Apologies for the long post
