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View Full Version : OT - Spray Painting Advice



Winston001
14-06-2004, 07:56 PM
This is a great forum. Experts on everything abound. So I wonder if anyone can help.

I have an air compressor (as I am sure most Kiwis do) and a high quality (cough) spray painting handpiece with bottle. All courtesy of Mitre 10.

This painting business looks an easy lark, I thought to myself, so I tried it. I used acrylic roofing paint, thinned with water by 10-15%.

Initially no paint came out at all. More thinning and shaking resulted in a sort of green mist which I had to accept as paint coverage. Very slow and tedious. In fact I picked up a brush later and doubled the speed of coverage.

Googled the subject and went to the library. No real explanations of the finer points of using spray paint equipment. Everyone assumes it all works and tells of the wonderful special effects you can achieve.

I think I have a 2mm nozzle. I suspect this is too small but that seems odd on a handyman piece of equipment. (yes, you can all jump in here with the appropriate witticisms)

Anybody done much of this?

Cheers
Winston001

Steve Askew
14-06-2004, 08:12 PM
The spray gun should have 2 knurled knobs at the back . One of them regulates the amount of air going into the gun & the other regulates the amount of paint that comes out the nozzle.
Have a play with those & just use water in the gun so you can have a play without making a mess.

Steve

Steve Askew
14-06-2004, 08:15 PM
Also you want about 40 psi delivered to the spray gun.

Steve

Winston001
14-06-2004, 08:26 PM
Thanks Steve. Yes, the knobs are there, and believe me, they were fiddled with until they came off. The handpiece still seemed to get blocked after about 10-15 minutes no matter what setting I used.

Your idea of experimenting with water is excellent.

I'm just looking for guidance before I attack the nozzle with a 4mm drill. Kind of a one-way modification so I'm hesitating. Air pressure isn't a problem hopefully. 2.5 hp compressor with 40litre tank.

metla
14-06-2004, 09:07 PM
Its a knack bought about by experience i do believe.

My last painting adventure was to disasemble a case and paint it a Holden metallic green,i had much the same problems,messed around with the 2 knobs and air-pressure untill my head hurt,then me younger brother happened to call in and after less then 20 seconds of fiddling had her set up perfectly.

I knew he would come in useful one day,surprised that it only took 23 years though.

Susan B
14-06-2004, 09:14 PM
> Initially no paint came out at all. More thinning and shaking resulted in a sort of green mist which I had to accept as paint coverage. Very slow and tedious. In fact I picked up a brush later and doubled the speed of coverage.

I don't know, and don't want to know, anything about spray painting but I just have to say that you do tell a good story, Winston. Had me in stitches here tonight. :D

dumdum
14-06-2004, 09:22 PM
Normally you would put roofing paint on with an airless set up,with no thinning of the paint,
I'll do my best to educate in the setting up of the gun you have Winston.

1)If there are(should be) two adjusting knobs on the back of the gun,screw them both shut(clockwise).One is for paint,(the lower of the two),the other for air(the top one)(actually for fan width).
2)If there is a knob on the bottom of the handle of gun(next to where air hose connects to gun),close this also.
3)Fill up your pot/bottle/cup,what ever you want to refer to it as,with paint,connect this to your airline,compressor going of course.
4) Now if there is a knob,as mentioned in #2, turn this on 3/4 to full.
Pulling the trigger at this stage should give you an idea as to whether you have the desired amount.If so go to next stage.
5)Hold your finger on the trigger(without looking directly at where paint comes out)pointing gun towards a clear space,unscrew the top knob about half way out.Go to next stage.
6)While still holding finger on trigger,unscrew the second or lower knob until the desired amount of paint comes out.You are almost set now.
7)If all goes well,you should be able to start painting.
8)Hold gun about 12inches away from the "job".Adjust paint up or down as required.Same for fan adjustment

Hope that gets you started, if not post back with more queries.

All the best
DD

somebody
14-06-2004, 09:25 PM
Depending on the design of the spray gun, it will need a precise setting to make the paint come out properly. If it's similar to a mini-version i've used (more of an airbrush actually), you need the air to go across the top of the nozzle at the right pressure, angle and height to make any paint come out.

Personally I prefer a roller/paintbrush, having painted 2 houses successfully using rollers (for walls, ceiling and roof), and paintbrushes for edges/corners. It also requires less coats, because you don't thin down the paint.

godfather
14-06-2004, 09:52 PM
Winston001

I feel that this is a severe treatment for the keypad on your phone, I really can't see the paint fixing the problem of too much graphite.

Please reconsider.

beetle
14-06-2004, 09:58 PM
must ask..... What are you painting??????

and if its a repaint of the tardis blue or red iis the preferred colours are they not???? green????
oh i get it camoflage? to go with the photo i have seen??? blending in thing?

the mind boggles really, and if you hand painted it any way is that not the way it should have been done???

things will all become clear in time i feel, er green in time or what ever colour you are painting.....

:D

dont forget to clean the gun as blocked nozzles have a tendency to stuff the sprayer...... gun / bottle not W001 i mean....

:p
beetle

Baldy
14-06-2004, 10:03 PM
I have had great results using an old Electrolux and Agee jar to hold the paint

Winston001
14-06-2004, 11:26 PM
Excellent thought Baldy. In fact I've got an old Electrolux painting attachment but have never been game to try it. I knew a guy who did an Anglia and swore by it - the paint job I mean.

Beetle - I'm now encouraged to put a photo of my work up for all to see. Will have to scan it first.

GF - TOO LATE............... - oops, thats shouting innit. Whose a naughty boy. ]:)

DD - thanks for the blow by blow instructions. I shall try to follow them but am not holding my breath :D

Winston001
14-06-2004, 11:45 PM
While not wishing to extend an extremely OT thread, I would like to at least hazard a guess at the functioning of a spray-painter. The device I mean, not the chap/ess at the end of it.

The air passes quite quickly across the end of a tube. The other end of said tube is immersed in paint. A venturi is formed at the open mouth of this tube and the resulting vacuum causes paint to rush up and occupy the space.

As we all know, paint abhors a vacuum - Electrolux, Nilfisk, Hoover - detests them all.

But I digress. And its late.
So, the paint rushes out of the tube into some very busy air which is trying to get outside through a 2mm pinhole. The various molecules escape in a mist which is shaped like a fan by the adapter on the front. This fan can be adjusted in some guns but I think mine is the common or garden variety.

The problem as I see it, is that
(a) the paint is too thick to suck, or
(b) the nozzle is too small.

My 4mm drill is looking very tempting at this point but, perforce, I shall hold back and calmly adopt the sound advice rendered this evening.

Thankyou all.

Rolfe Harris

mikebartnz
15-06-2004, 03:02 AM
If you thin the paint ( by degrees) until the water mixes in almost straight away you should have about the right consistancy. An airless gun from a hire company would be better for a roof though but save that gun for when you need to repaint the car.

dumdum
15-06-2004, 08:30 AM
Winston,..
Is the breather clear. If this is blocked no paint will come out.Found on top of lid.

Winston001
15-06-2004, 09:27 AM
Mate, the breather is so bloody clear that I covered myself with paint when I vigorously shook the gun in frustration. It does not seal onto the bottle - made that way. But there is plenty of paint.

Too cold? Nope, I'm in Southland so that can't be it. ;)

Jester
15-06-2004, 10:07 AM
This is another whats wrong wif my fridge thread isn't it!!?? Just as entertaining too, I am holding on here, waiting for the next installment, so at least I will have some idea (although probably misguided) as to what to do if I ever find myself needing to spraypaint something.

Quote of the thread so far:

"As we all know, paint abhors a vacuum - Electrolux, Nilfisk, Hoover - detests them all."

Young Tom
15-06-2004, 01:20 PM
My dear Win,the kit you have is suitable for lacquer or the enamel used on cars.
As suggested the airless spray or the wagner gun suited your job is the way to go
Better still stay back at work for an hour and pay someone with the proper tools.;)

Winston001
15-06-2004, 01:37 PM
> Better still stay back at work for an hour and pay
> someone with the proper tools.;)

Golly. It wouldn't cost that much, surely??? :O

Young Tom
15-06-2004, 01:45 PM
You right again of course,make it half an hour.;)

Winston001
19-06-2004, 04:01 PM
For anyone interested, I've put a photo up on Sal's site showing my painting project and a small staff member :D

http://sal.neoburn.net/imagef1/files/Jenny_-_Snow_-_Aw_005_(Medium).jpg

beetle
19-06-2004, 04:05 PM
W001!

do you still have outhouse's down your way then???? :p

no such thing as running water in that cold low down peice of the island then???

:D

LOL

beetle

Steve Askew
19-06-2004, 05:15 PM
It looks good from here,looks like somewhere for kids to stand while waiting for the school bus? Whats that white stuff? overspray maybe?


Steve

godfather
19-06-2004, 06:06 PM
How could you be so unkind towards the Civic amenities in the fair city of Invercargill, people?

Plainly the photograph is the Invercargill Town Hall on a mid-summers day.

Those people making comments have obviously never been there!

Tom McB
19-06-2004, 07:20 PM
I've done some airbrushing on aircraft models using a Badger, the principles are very similar. I have an external mix brush which I've found a bit fiddly to adjust so have switched to internal mix.

Too much air and you get a spotty effect. Too much paint or water (acrylics) and the finish is runny (also applies if the nozzle is too close to the work area). Too thick and you hardly get anything at all (I manage at 25psi, any lower causes problems). I've given up on enamels due to the clean up effort afterwards.

Of course, I use small glass paint bottles and can see if the paint is able to be drawn properly.

When I'm not sure of the mix ratio, I tend to start at a thinner mix (at least I can get a thin coat applied). If thicker, I end up with more "gunk" than airbrushing.

Mix the paint in a separate tin then filter thru a sieve or an old curtain netting.

m2cw

all the best
t

Winston001
19-06-2004, 07:49 PM
Thanks Tom, I'll remember that tip.

GF - that is most unkind. It's the Invercargill Bus station, as you very well know. The Town Hall is in the background - you can see Mayor Tim through the door. :D

And Steve - I'm a bit puzzled: white stuff? Well.......there's the normal groundcover I suppose..........is that what you mean? Makes it easier for tracking varmints.......such as JAFFAs.

Beetle - good guess. Close but no cigar. However you will be aware that progress means we now have heated out-houses - hence the chimney.

So, the purpose of this carefully sprayed structure is......TA DA........a Pumpshed. Prosaic but true.

I needed a new pumpshed and decided it should look a bit different. Originally I thought of a gun emplacement on top, or a sort of guard tower. But realistically a little cottage seemed easier. Also meant the children could participate with painting windows, flower-box etc.

Now all I have to do is move the darned thing to the site. However it was a lot easier to construct beside the garage than 50 meters away down a gully. Pity thats where the water is.

Cheers
Winston001