What caused this?

GasX

GasX

New Member
I was painting some bike parts last night and after a couple of coats of black semi gloss engine paint, the paint changed appearance. Instead of a nice uniform black, it looks like a mist of fine grey dust blew across the surface.
Any idea why this might happen?

It was about 70 degrees outside, but humidity might have been high...
 

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ok....

my guess, NOT tried and true personal experience,

'with ceramic' might be the clue...

It was sprayed too light/dry to wet the surface and the ceramic properties didn't settled well enough into the medium/solvents...

How's that sound for a theory???

lol
I'd be sure to get a 2nd opinion before going in for the operation! :-)
rc
 
could have been a few things
1 too dry a spray technique
2 humidity trapped in your spray , yes it can get in there just by moving through the air
3 paint flashed off too quickly trapping solvent beneath
4 your top coat could have softened your primer an brought its pigments to the surface a common problem for example: when trying to spray light colors over reds or dark primers but rarely seen when using light color prime an dark color, but still possible .
hope that helps explain it
Gary
 
It looks like oil contamination which will repel the primer. Alcohol will not remove silicone based oil. You should use an acid based conversion coating such as DuPont 5718S.
 
The primer coat looked great, I like the humidity theory. When I was finishing up, there were some low lying clouds flying by - almost fog.

I baked it in the Florida sun all day today. Maybe another coat or two will fix it...

Fingers crossed
 
most times your primer will look great untill color hits it an those thinners set in all paints achieve some chemical an mechanical (the reason for sanding) adheision.
but you know the conditions at time of spraying be sure to resand an maybe let dry someplace cooler .
 
It's a process for sure. Remember not to rush your paint jobs. From the frosted look it looks like your either not putting enough paint or your distance from the frame is too far. Your not going to get the look you want on the first try. Prep work is key before adding the color coats. Prep, prime, prep and then paint. After your done painting hit it with some high gloss clear hardener. Let it sit for a few days to cure and get nice and hard. Then give your bike a wet sand with 3300grip paper. After the wet sand and some polish you should have a professional looking paint job. :)
 
the quality of a topcoat can not exceed it's ability to adhere to the substrate upon which it's applied.

I've never seen where alcohol was an effective solvent for cleaning anything related to mechanical parts.

use lacquer thinner or acetone.

...good idea to wet sand w 3k then shoot a clear over the top... if the paint is stable.

far better quality product available when u get away from the rattle cans... with a very few exceptions.

even the cheapest airbrushes available are superior to rattle cans... and u can run one off a car's spare tire !

as said above, it's possible that your last spray pass, after everything had good coverage, and a nice wetted surface, was held too far and was too lite, possibly causing the atomized spray to dryfall on the surface leaving a bit of coarseness to the topcoat.
...I'm frequently guilty of doing that... just one more little bit... and it botches a job already well done! lol

paintwork is great fun! a difficult skill to master, but results are almost always an improvement. :-)

Best
rc
 
look's good to me. i thought that was the way it supposed to be. every time i try to paint the more i paint the worse it get's here in warm dry so.cal.
 
rustycase said:
even the cheapest airbrushes available are superior to rattle cans... and u can run one off a car's spare tire !

rc
Click to expand...

yes I guess you could ,I had never ever considered that as an option to run my airbrush, only problem is it would be like the old vw that ran its wipers off the tire pressure eventually it stops.
 
Thats subjective last one I did that way 4 cans at roughly 6 bucks a can 24 bucks, pint of a cheaper color about 36 bucks an it does more . it all comes down to what you want but if you use anything thats base clear the clear an hardener will get you clear a pint about 30 an you have to buy hardener in pints at about 20 an maybe only need 1/4 of that to fire the clear .
cheapest clear i use 140 a gal an its hardener 35 a qt 4 to 1 mix ratio.
 
Well that's true, gnu, there's an end to all good things! lol
especially the cheap ones!
but out here in Kalifornia, we don't got so many vdub tires around, but we DO got a lotta HUGE boulevard Komando tires off suv's and pu's that would more than paint a mc...
I probly got 5 or 6 compressors here, so I wouldn't need to run off a static system, but I DO have the hose to do so if all else fails.
...ur post above sounds like you are using quality product. I'm using stuff that sells for $40 a gal from a regional paint store for DTM applications. No metallics, but they got a full range of color. They paint aircraft with the stuff...
but I'm a cheapskate... I buy the mis-tints for $5 a gal and tint em some direction I can use.
Gonna be a whole new scenario for me, next time I get by there. Last time I bought the last alkyd paint they would have in stock. Ever.
New product lines and all water-based now.
Best
rc
 
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