Aerosol painting problems.
The Technical Manager
with a matt finish and slightly rough looking compared to the smooth and
shiny finish of the rest of the car directly after painting. The paint
is question is a solid colour and doesn't require a lacquer. The surface
was coated with primer using several thin coats before smoothing down
with 1500 grit wet and dry. The topcoats were built up using 4 thin
layers where the previous layer was left to dry for about 10 minutes
before applying a fresh coat. What is the reason for the rough matt
effect and how should it be rectified ? I have been tempted to leave the
paint to dry for a week and rub down using 1500 grit wet and dry before
applying a final topcoat. This will be left for two weeks before rubbing
down with T-CUT. Is this the best approach ?
MrCheerful
The above is the way to save what you have done. Generally each coat
should only flash off before the next coat. (about a minute max)
If you spray from too far away you get rough finish.
I usually expect to put on about 15 coats from an aerosol to get the
right result.
Depending on the job I would then finish with wet 600/800/1200 then
fine/ultrafine rubbing compound then polish.
The primer coat should not usually need to be rubbed down with
anything finer than 400 grit.
HTH
MrCheerful
Stephen Hull
Sounds like the paint is "blooming" because it's too cold and it's not
atomising properly due to incorrect temperatures, Aerosol paint will
always dry dull and rough under these conditions, Try warming up the
area and try again.
Aerosols are particularly susceptible to blooming due to the solvent
viscosity being extra thin in order to pass through an aerosol nozzle,
Although they generally consist of good quality solvents that give a
good shine they must be applied at room temperature or above to avoid
blooming.
It may be possible to polish it back first before attempting a respray.
Primer can be rubbed down with a coarser grade than 1500, 1500 is
more beneficial on finishing coats when a flat and polish is in order to
remove minor imperfections etc, Try using 800 or 600 and flat wet with a
little soap to ease lubrication and avoid clogging up the paper.
Flatting aerosol paint can be done the next day in most cases, There is
no real advantage in waiting a week or more because the paint would not
have softened any paint underneath sufficiently to warrant waiting for
it to dry right through.
Steve.
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"The Technical Manager" <tec...@yahoo.com> wrote in message
news:3E89A5D6...@yahoo.com...
If I HAVE to use a spray can then I just can it on thick and cut it down
with G3 afterwards. Always seemed good enough to me. This isn't the right
way BTW just a way that seems to work lol
The Technical Manager
> In message <3E89A5D6...@yahoo.com>
> The Technical Manager <tec...@yahoo.com> wrote:
>
> >Whenever I spray paint a body panel using an aerosol, the paint ends up
> >with a matt finish and slightly rough looking compared to the smooth and
> >shiny finish of the rest of the car directly after painting. The paint
> >is question is a solid colour and doesn't require a lacquer. The surface
> >was coated with primer using several thin coats before smoothing down
> >with 1500 grit wet and dry. The topcoats were built up using 4 thin
> >layers where the previous layer was left to dry for about 10 minutes
> >before applying a fresh coat. What is the reason for the rough matt
> >effect and how should it be rectified ? I have been tempted to leave the
> >paint to dry for a week and rub down using 1500 grit wet and dry before
> >applying a final topcoat. This will be left for two weeks before rubbing
> >down with T-CUT. Is this the best approach ?
> >
>
> Sounds like the paint is "blooming" because it's too cold and it's not
> atomising properly due to incorrect temperatures, Aerosol paint will
> always dry dull and rough under these conditions, Try warming up the
> area and try again.
I was suspecting that low temperature was affecting something even on a warm
spring day and that the paint was hitting the car in the form of droplets
rather than a fine mist. Would warming the aerosol by soaking it in a bowl
of warm water help ?
Stephen Hull
The Technical Manager <tec...@yahoo.com> wrote:
[snip]
>> Sounds like the paint is "blooming" because it's too cold and it's not
>> atomising properly due to incorrect temperatures, Aerosol paint will
>> always dry dull and rough under these conditions, Try warming up the
>> area and try again.
>
>I was suspecting that low temperature was affecting something even on a warm
>spring day and that the paint was hitting the car in the form of droplets
>rather than a fine mist. Would warming the aerosol by soaking it in a bowl
>of warm water help ?
>
Low temperature thickens paint in the aerosol so it'll struggle to come
out the spray nozzle cleanly, If you leave the aerosol indoors overnight
at minimum room temperature it will be warm enough to use the next day.
Although warming the aerosol indeed helps to thin paint and it will
atomise correctly you'll still have the same problem with cold or damp,
If it's sprayed on cold steel it's likely to just bloom again even with
improved viscosity caused by heating.
Remembering several thin coats are always better than one thick as it
allows the finish to be more manageable.
Mike Faithfull
news:3E89A5D6...@yahoo.com...
> Whenever I spray paint a body panel using an aerosol, the paint ends up
> with a matt finish and slightly rough looking compared to the smooth and
> shiny finish of the rest of the car directly after painting.
I presume this is a "proper" aerosol mixed and filled by your local Paint
Factors and not one of those things you buy in the motor accessories shop?
Whatever, I suspect you may be paranoid about forming runs in the paint and
are spraying it too lightly and/or from too far away. Cans don't perform
like a compressed air sprayer (with which, incidentally, I am totally
incapable!) In my youth I resprayed a Triumph motorcycle from cans and it
ended up like sandpaper! By about the sixth can I was getting it somewhere
near right - it cost a fortune!!
Fred
Guy King
from "Fred" <Dont...@hidden.co.us> contains these words:
> This is an aerosol painting problem!
> http://www.thesun.co.uk/article/0,,2-2003150899,00.html
I think you'll find that's an arsehole painting problem.
--
Skipweasel:-
"...and ninthly...."
Spog
the front of my bonnet.
The primer has gone on well, and I'm trying to put on the metallic
paint using a Halford's aerosol. Now it's supposed to be a dark
metallic blue (Java Blue)
However, the first coat was bright blue - I thought there was a
problem with a paint at first. However, spraying onto a piece of paper
and getting a thick dribbly lump shows the correct colour with the
metallic flakes. But this is just not appearing on the bodywork.
My thoughts are:
Insufficent shaking of can first (though I did the 2 mins)
Too cold weather (it's a bit chilly today)
Too windy
Any thoughts/suggestions?
Thanks
spog
The Technical Manager
I am tempted to say its Halfords paint. My experience with their paints
have been chequered. Colour mismatches are quite commonplace.
Are you using the right colour primer ?
Spog
> > The primer has gone on well, and I'm trying to put on the metallic
> > paint using a Halford's aerosol. Now it's supposed to be a dark
> > metallic blue (Java Blue)
> >
> > However, the first coat was bright blue - I thought there was a
> > problem with a paint at first. However, spraying onto a piece of paper
> > and getting a thick dribbly lump shows the correct colour with the
> > metallic flakes. But this is just not appearing on the bodywork.
>
> I am tempted to say its Halfords paint. My experience with their paints
> have been chequered. Colour mismatches are quite commonplace.
>
> Are you using the right colour primer ?
Thanks for the reply. I'm using grey primer.
I think it is the right colour - if I spray from 1" onto a piece of
plastic, it forms a puddle of the right colour, complete with metallic
flecks - it's just when it goes on the bonnet it's like only some of
the pigment is getting that far.
I'm coming to the conclusion that perhaps it was a bit too windy and
only the heavier particles were getting as far as the metal. I'm
tempted to try again on a less windy day.
But I'm open to the thoughts of those more experienced than me.
Spog
Jacqui Caren
news:8a719e14.0304...@posting.google.com:
> Im coming to the conclusion that perhaps it was a bit too windy and
> only the heavier particles were getting as far as the metal. I'm
> tempted to try again on a less windy day.
Spraying on a windy day in the open !!!!
If you don;t have a garage the
1) get a BIG platic bag - I know sounds daft but it does work
for smallish areas
or
2) use a bigg(ish) cardboard box with a hole but out of the bottom
to act as a windshield.
Before we had the "shed" we used to fasten a builder sheet 18' x10'
across the car doors then use some poles (brooms etc) to make
a 'tent'. You can paint in there without worrying about wind dust etc.
Painting in the wind is a no-no - we made the mistake of spraying
in a dusty garage once - the crap in the finish :-(
Nowadays we clean, dehumidify and heat before painting - except
when slapping on hammerite :-)