Colin_P
Guru
That is due to contaminaton, usually silicon.
What you need to do is wipe the whole frame down to remove every invisible trace of any contamination. I say invisible because while it may look thoroughly clean it obviously isn't. And when you wipe it down, looking at the level of contamination there there, you will need to use many cloths (kitchen roll is good) so you don't spread the contamination all over the place.
This is what I do and would do with that bike...
1, Wipe down with cellulose thinners (about £10 for 5 litres from a good motor factors, you'll use very little but it is a very good general purpose to cleaning non painted oily bits and will last you years). Alternatively pinch your Mrs nail varnish remover and use that...
2, Wipe it down again with celly thinners
3, And again
4, Wipe it down with some stuff called "panel wipe" again from the motor factors, about £15. Alternatively get a few cans of aerosol automotive brake cleaner, these are about £3 each
5, Panel wipe it again
6, And again
As for spraying in cold temps in an unheated workshop, it can be very difficult to avoid what is called "bloom", this is when atmospheric moisture condenses into the paint film as the solvents are evapourating. The solvents rapidly cool the paint as they evapourate providing the perfect conditions for the moisture to condense onto and into that cold surface. "Bloom" usually manifests itself by turning the paint white cloudy. Not a lot you can do unfortantely although you might be able to get away with heating the frame with (ironically) an electric painter stripper gun and then (from a distance) continue to dry and keep the paint warm (for up to 15-20 mins) as the solvent flashes off / the paint dries. Alternatively pinch the Mrs hairdrier....
As for the paint itself I'd use an etch primer on the newly panel wiped steel (2 coats) then a put the top coat(s) on.
But what I'd really do is leave the paining well alone until things warm up a bit and concentrate your effort in mocking up / trial fitting the bike, fitting everything you may need to fit to the frame and making sure it all fits and works before you damage the newly painted frame like someone I know....
What you need to do is wipe the whole frame down to remove every invisible trace of any contamination. I say invisible because while it may look thoroughly clean it obviously isn't. And when you wipe it down, looking at the level of contamination there there, you will need to use many cloths (kitchen roll is good) so you don't spread the contamination all over the place.
This is what I do and would do with that bike...
1, Wipe down with cellulose thinners (about £10 for 5 litres from a good motor factors, you'll use very little but it is a very good general purpose to cleaning non painted oily bits and will last you years). Alternatively pinch your Mrs nail varnish remover and use that...
2, Wipe it down again with celly thinners
3, And again
4, Wipe it down with some stuff called "panel wipe" again from the motor factors, about £15. Alternatively get a few cans of aerosol automotive brake cleaner, these are about £3 each
5, Panel wipe it again
6, And again
As for spraying in cold temps in an unheated workshop, it can be very difficult to avoid what is called "bloom", this is when atmospheric moisture condenses into the paint film as the solvents are evapourating. The solvents rapidly cool the paint as they evapourate providing the perfect conditions for the moisture to condense onto and into that cold surface. "Bloom" usually manifests itself by turning the paint white cloudy. Not a lot you can do unfortantely although you might be able to get away with heating the frame with (ironically) an electric painter stripper gun and then (from a distance) continue to dry and keep the paint warm (for up to 15-20 mins) as the solvent flashes off / the paint dries. Alternatively pinch the Mrs hairdrier....
As for the paint itself I'd use an etch primer on the newly panel wiped steel (2 coats) then a put the top coat(s) on.
But what I'd really do is leave the paining well alone until things warm up a bit and concentrate your effort in mocking up / trial fitting the bike, fitting everything you may need to fit to the frame and making sure it all fits and works before you damage the newly painted frame like someone I know....