| View previous topic :: View next topic |
| Author |
Message |
Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
|
 Posted: Sun Nov 04, 2007 1:53 pm Post subject: painting problems |
 |
|
can someone tell me what im doing wrong. Im getting white patches/lines on my car surface as i spray paint it...it goes on shiny but as i do my next pass with 50% overlap these patches start to appear...could too much or too little thinner do this??.. .. Im using a gravity feed gun, thought that was the problem so i bought another one, which gave me a better spray pattern but still these white cloudy patches/lines..they dont buff out either they actually seem to get worse after cutting
originally i used a 1.4mm nozzle now a 1.7mm still same problems.
The paint is a black acrylic. If i were too guess ide say something wrong with air supply perhaps water vapour in the compressor line or too high humidty..although i know people who spray in high humidity with no problems.
Also ive heard conflicting views , one says lightly spray your spray room/ garage floor with water to prevent airborne dust particles, whereas others say keep room as dry as possible.??
any ideas?..techniques?
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
|
| Back to top |
|
 |
PORSCHEV
Joined: 02 Nov 2002
Posts: 1901
Location: Cedar Lake Nova Scotia, Canada
|
| Posted: Mon Nov 05, 2007 2:12 am Post subject: |
|
|
Tell me more about the paint you are using. Are you using the right activator and the proper reducer? What mix ratio are you using and what does the maker call for?
I would rule out water contaimination as that looks different then clouds. Is the paint solid black or does it have some metalics?
_________________
1976 924
5 lug conversion, 17'C2 wheels,custom body work,327 vette engine.
1978-#53 "D" track racer. |
|
| Back to top |
|
|
924aussie
Joined: 02 Feb 2006
Posts: 1009
Location: Chinchilla Queensland Australia
|
| Posted: Mon Nov 05, 2007 11:27 am Post subject: |
|
|
Scorpio,
Go down to supercheap and buy the spray painting book. Done by the guy from NSW TAFE.
Enrol in a 6 week Spray Painting Course ... night time at Ithaca college across from the Broncos.
1.. What is the compressor you are using
2.. what is the brand of the thinners
3.. what is the brand of the Acrylic Laquer ... should be the same
4... what mixing ratio are you using
5.. What paint was it previously painted in
6.. If you have been spraying outdoors in the recent weather we have had it may be a humidity problem
7.. If it was indoors what was the approx temperature of the panels
Alan 
_________________
green 924 .. 1980 rego 924PSH
1998 Mopar Neon ... sick
2003 Challenger / Montery 4WD
1995 Hyundai Scoupe ... sold
1998 Nissan Silvia ... sons back from OS he has taken it
BIG BLOODY MOTORHOME 300zx Sold
1980 Fire truck Sold |
|
| Back to top |
|
|
puddlejumper
Joined: 01 Nov 2007
Posts: 8
Location: Minnesota
|
| Posted: Mon Nov 05, 2007 12:46 pm Post subject: |
|
|
Throw some pics up.
_________________
If one does not fail at times, then one has not challenged himself.
Ferdinand Porsche |
|
| Back to top |
|
|
Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
|
| Posted: Mon Nov 05, 2007 12:56 pm Post subject: |
|
|
How did you clean the surface?..could silicone from old wax be causing it?
_________________
"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
|
| Back to top |
|
|
924aussie
Joined: 02 Feb 2006
Posts: 1009
Location: Chinchilla Queensland Australia
|
|
| Back to top |
|
|
Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
|
| Posted: Tue Nov 06, 2007 12:42 pm Post subject: |
|
|
THE PAINT IS SEPTONE ACRYLIC.
1 is to 1.5 paint to thinner ratio
They recommend a 2mm nozzle on the tin but i think my 1.7 even the 1.4 is sufficient enough.
The thinner was a different brand but as of yesterday ive gone out and bought a SEPTONE thinner aswell as a inline water trap
 [/img]
THE DAMAGE
the photo looks alot worse then it really is but it illustrates the problem, im spraying my suzuki bonnet as practice before hitting the porsche, ive sprayed a couple of cars before and they turned out great (used different paints, prob wasnt as humid), im using the cheaper paint here $80 , 4 litres because the suzuki is just practice. I tried spraying just air onto the right corner to illustrate the effect , sprayed it as paint was drying and you could visibly see the cloudy bit forming, does this mean the air quality is bad..ie too moist or the paint and or thinner is bad? On the coat you see i did go overboard to illustrate whats going on, previous coats werent as bad but still shi7. overlap of coats was fine 50% overlap .The centre uneven bit is masked off blue strip
| Quote: | | How did you clean the surface?..could silicone from old wax be causing it? |
The surface was wet sanded then i used septone grease and wax remover so im pretty sure it ist the problem
| Quote: |
Go down to supercheap and buy the spray painting book. Done by the guy from NSW TAFE.
Enrol in a 6 week Spray Painting Course ... night time at Ithaca college across from the Broncos.
1.. What is the compressor you are using
2.. what is the brand of the thinners
3.. what is the brand of the Acrylic Laquer ... should be the same
4... what mixing ratio are you using
5.. What paint was it previously painted in
6.. If you have been spraying outdoors in the recent weather we have had it may be a humidity problem
7.. If it was indoors what was the approx temperature of the panels |
Hey alan i was actually thinking of the ithaca spray course but 6 weeks is just a bit too much at the moment with other commitments. Im attempting the whole self taught method and have been reading up a fairbit, i dont seem to have any other problems but the white cloudy bands. Compressor is a 40 litre, perhaps slightly small but airflow pressure seems fine.
Ive tried a variety of different thining ratios from 1 to 1 all the way to almost 3 is too one..I was told the more thinner the better generally to an extent ( not for the environment though !). Ive been spraying indoors and yes it has been pretty humid...can says dont spray above 80% humidity, Today is 59% humidity and in the last week i dont think it got above 70%
| Quote: | Is the paint solid black or does it have some metalics?
its a solid black |
Here in brisbane a spray job costs in the thousands and ive asked around but apparently noone here does hire spray booths anymore..not good
Thanks all for the help!!
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
|
| Back to top |
|
|
Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
|
| Posted: Tue Nov 06, 2007 1:41 pm Post subject: |
|
|
Apparently it's something in the air supply if spraying just air causes it.
Do you drain the compressors' tank after each use? Was the air line used for anything else since the last paintjob?- Maybe the line's contaminated with oil from the compressor..? Is the compressor using/consuming oil?
_________________
"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
|
| Back to top |
|
|
924aussie
Joined: 02 Feb 2006
Posts: 1009
Location: Chinchilla Queensland Australia
|
| Posted: Tue Nov 06, 2007 2:39 pm Post subject: |
|
|
| Smoothie wrote: | Apparently it's something in the air supply if spraying just air causes it.
Do you drain the compressors' tank after each use? Was the air line used for anything else since the last paintjob?- Maybe the line's contaminated with oil from the compressor..? Is the compressor using/consuming oil? |
As smoothie says Air is air nothing else ...
Course is three hours once a week for 6 weeks of a night time 5.30 to 9pm
Replace the gun with an air duster / blower and see if anything comes out.
I have a portable spray booth but it only fits bikes in it at the moment. I am thinking of putting slide outs in it like a motorhome.
Alan
_________________
green 924 .. 1980 rego 924PSH
1998 Mopar Neon ... sick
2003 Challenger / Montery 4WD
1995 Hyundai Scoupe ... sold
1998 Nissan Silvia ... sons back from OS he has taken it
BIG BLOODY MOTORHOME 300zx Sold
1980 Fire truck Sold |
|
| Back to top |
|
|
Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
|
| Posted: Tue Nov 06, 2007 2:41 pm Post subject: |
|
|
| Quote: | Apparently it's something in the air supply if spraying just air causes it.
Do you drain the compressors' tank after each use? Was the air line used for anything else since the last paintjob?- Maybe the line's contaminated with oil from the compressor..? Is the compressor using/consuming oil?
|
Its a new compressor, i drain the tank before every use allowing water to drip out. and havent used the pipe for anything else. I dont think the compressor is consuming any oil. That lower right corner which i sprayed with air was straight after putting a coat of black on it..ie the paint wasnt dry, perhaps the air is fine and there is a problem with the thinner..im going to try the new thinner with the inline water trap...will the water trap also trap any oils?
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
|
| Back to top |
|
|
Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
|
| Posted: Tue Nov 06, 2007 3:15 pm Post subject: |
|
|
Yes, the trap will catch oil and water. I use two, one at each end of the hose.
_________________
"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
|
| Back to top |
|
|
924aussie
Joined: 02 Feb 2006
Posts: 1009
Location: Chinchilla Queensland Australia
|
| Posted: Tue Nov 06, 2007 3:42 pm Post subject: |
|
|
just curious .... what was the other brand and what was the ratio you mixed it at.
Alan
_________________
green 924 .. 1980 rego 924PSH
1998 Mopar Neon ... sick
2003 Challenger / Montery 4WD
1995 Hyundai Scoupe ... sold
1998 Nissan Silvia ... sons back from OS he has taken it
BIG BLOODY MOTORHOME 300zx Sold
1980 Fire truck Sold |
|
| Back to top |
|
|
924aussie
Joined: 02 Feb 2006
Posts: 1009
Location: Chinchilla Queensland Australia
|
| Posted: Tue Nov 06, 2007 7:05 pm Post subject: |
|
|
PPG also known here as Dulux, ICI Duco etc
If you do this FREE online course you will notice that some parts are repeated ... just be patient 
http://corporateportal.ppg.com/NA/Refinish/PPGRefinish/5-0-Training/5-7-OnlineTraining/
Online Training
Too busy to take time away from work to your increase your knowledge and hone your skills? Then consider taking of one of our PPG's online training courses. Now you can study at home, at night, on weekends—anytime you choose.
Here's a list of the courses currently available online. To learn more about a course, simply click a course title.
Course Titles
Color 21
Safety
Fundamentals
Undercoats and Topcoats
Repair Process
Distributor Troubleshooting
Elearning SAMPLER
PPG Color Variant System
Nexa Autocolor World Car Colour System
One Choice™ Plastic Prep System
Delfleet Essential
Actually the real reason of your problem is probaly that you are not using the recommended Spray Gun as per the Porsche Workshop Equipment list
Final Coat Spray Gun SATA Jet/B order number 3228 
Alan
_________________
green 924 .. 1980 rego 924PSH
1998 Mopar Neon ... sick
2003 Challenger / Montery 4WD
1995 Hyundai Scoupe ... sold
1998 Nissan Silvia ... sons back from OS he has taken it
BIG BLOODY MOTORHOME 300zx Sold
1980 Fire truck Sold |
|
| Back to top |
|
|
emoore924
Joined: 13 Apr 2004
Posts: 2822
|
| Posted: Sat Nov 10, 2007 4:42 am Post subject: |
|
|
| PSI? |
|
| Back to top |
|
|
PORSCHEV
Joined: 02 Nov 2002
Posts: 1901
Location: Cedar Lake Nova Scotia, Canada
|
| Posted: Sat Nov 10, 2007 6:13 am Post subject: |
|
|
| Scorpio wrote: | THE PAINT IS SEPTONE ACRYLIC.
1 is to 1.5 paint to thinner ratio
They recommend a 2mm nozzle on the tin but i think my 1.7 even the 1.4 is sufficient enough.
The thinner was a different brand but as of yesterday ive gone out and bought a SEPTONE thinner aswell as a inline water trap
|
Your not being clear enough on the mixing ratio.
If it were an acrylic lacquer I would think it should take an activator. The way I understand your ratio you mention it would be 1.5 liters of paint to 1 liter of thinner which would be very thin to spray. Most lacquers are 10-20% thinner.
I have painted hundreds of cars and I have never seen anything like that! Oil contaimination makes fish eyes...so it's not that for certain.
Water in the air line will form small droplets as you are spaying.
The product info also says "It is not suitable for application over air dry enamels or nitrocellulose lacquers. Septone Acrylic Lacquer is ideal for the DIY enthusiast due to its ease of application and quick drying properties."
_________________
1976 924
5 lug conversion, 17'C2 wheels,custom body work,327 vette engine.
1978-#53 "D" track racer. |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
924 FAQ (Technical)
