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Do's and Don'ts of Spray Painting.

Posted:
Wed Nov 15, 2006 1:08 pm
by NightCap
Is there a thread or discription of how to use one of those gravity fed sprayers to paint with car paint or varnish etc?

How to do it and clean the sprayer etc?

Could save me a ton of time puting on a dozen coats.

Posted:
Wed Nov 15, 2006 1:12 pm
by rbeemer
Nitecap,
I would PM Doug Hodder, but you can get a good deal of knowledge from a quick search of the internet.

Posted:
Wed Nov 15, 2006 3:31 pm
by asianflava
I used a cup gun to spray polyurethane a gravity gun probably isn't too different. Cleaning it depends on how anal you want to get. Some people like to completely disassemble the gun and soak all the parts and gun in solvent. I didn't do too much, I ran solvent thru the gun, then I removed tha needle and nozzle and soaked just those. I'm using a HF special, I think it cost me $12.
I started with what the manual recommended but, I found that I was using way too much pressure, I had a ton of overspray. I had to play around with the gun in order to get it spraying right. I'd also recommend getting a drier for your compressor, if you don't have one already.
Re: Do's and Don'ts of Spray Painting.

Posted:
Wed Nov 15, 2006 3:53 pm
by halfdome, Danny
NightCap wrote:Is there a thread or discription of how to use one of those gravity fed sprayers to paint with car paint or varnish etc?

How to do it and clean the sprayer etc?

Could save me a ton of time puting on a dozen coats.
I hope you have a HVLP gravity cup gun otherwise everything within 5 miles will get a dusting. The cheap ones work fine. If it doesn't have a small pressure gauge that can be adjusted at the guns fitting I would get one and keep the air pressure as low as the instructions state. Don't get in any hurry, light coats are better than thick coats. You also need a water trap 25 feet from the compressor to keep moisture ( we may hit a record for rain tonight) from contaminating the finish. Hook your air hose for your spray gun on after that. A clean gun makes a clean finish a dirty gun won't work properly. Have fun,
Danny

Posted:
Wed Nov 15, 2006 4:48 pm
by Podunkfla
NightCap... This link is one of the better explanations I've seen on setting up and using HVLP spray guns:
http://www.hotrodders.com/kb/body-exter ... aygun.html 

Posted:
Thu Nov 16, 2006 5:48 pm
by NightCap
Thanks for the links and information. I did pick up this sprayer at harbor freight.
INDUSTRIAL PAINT SPRAY GUN
Specially designed to deliver professional results with light and medium viscosity finishes.

Posted:
Thu Nov 16, 2006 9:17 pm
by Podunkfla
NightCap wrote:Thanks for the links and information. I did pick up this sprayer at harbor freight.

INDUSTRIAL PAINT SPRAY GUN
Specially designed to deliver professional results with light and medium viscosity finishes.
NightCap... It's a little late... But I have to suggest you may be happier swapping in that gun for one of these from HF:
http://www.harborfreight.com/cpi/ctaf/d ... mber=43430
http://www.harborfreight.com/cpi/ctaf/d ... mber=93305
I have two of the first one... and one of the second. They are great sprayguns for the money. (I have a $400.+ Binks too... and these work just as well. The pro Binks may last longer. but, the HF guns are pretty darn good). A gravity feed HVLP gun with pressure regulator is a lot easier to use than a conventional suction feed gun. And, HVLP wastes a lot less material, doesn't get overspray all over everything in the shop, and doesn't fog up your spray area near as bad with overspray... All attributes of older high pressure conventional guns like it looks like you have. Just a friendly suggestion from someone who uses them.
friend ~ Brick

Posted:
Thu Nov 16, 2006 9:26 pm
by halfdome, Danny
Podunkfla wrote:NightCap wrote:Thanks for the links and information. I did pick up this sprayer at harbor freight.

INDUSTRIAL PAINT SPRAY GUN
Specially designed to deliver professional results with light and medium viscosity finishes.
NightCap... It's a little late... But I have to suggest you may be happier swapping in that gun for one of these from HF:
http://www.harborfreight.com/cpi/ctaf/d ... mber=43430http://www.harborfreight.com/cpi/ctaf/d ... mber=93305I have two of the first one... and one of the second. They are great sprayguns for the money. (I have a $400.+ Binks too... and these work just as well. The pro Binks may last longer. but, the HF guns are pretty darn good). A gravity feed HVLP gun with pressure regulator is a lot easier to use than a conventional suction feed gun. And, HVLP wastes a lot less material, doesn't get overspray all over everything in the shop, and doesn't fog up your spray area near as bad with overspray... All attributes of older high pressure conventional guns like it looks like you have. Just a friendly suggestion from someone who uses them.
friend ~ Brick
I couldn't agree more on the guns. I have a gun like you pictured and only use it for spraying contact cement, works great for that. Since Harbor Freight has a store in town I'd go back and get the first one Brick suggested.
Danny

Posted:
Fri Nov 17, 2006 12:16 am
by NightCap
Roger That. I'll exchange it tomorrow. Thanks guys.

Posted:
Fri Nov 17, 2006 12:48 am
by doug hodder
Amen to the above on the HVLP guns...suction cup guns are really old school anymore...but I do have 2 and use them regularly. Gravity guns only need like 18# pressure at the gun...and remember that if you don't have a gauge at the gun, you are not getting an accurate reading if you are using like 25' of hose...for cleaning, I use cheap lacquer thinner, I buy it in 5 gallon containers as I use it to clean up a lot of stuff. pour out the leftover paint from the pot, dump in the lacquer thinner, like 1/2 cup + put the cap on....shake it up and start running it through the gun...dial in more material on your controls to run more through...pull the cap on the end, make sure it is all cleaned out...run another load...through...it should spray absolutely clear. wipe down the cup, gun etc. again with the lacquer thinner. If done correctly...I get several paint jobs out of it before I need to tear it down and really clean it up. Before I spray another project, I also dump in some lacquer thinner and make sure it is spraying correctly prior to catalyzing any paint. I'm sure not everyone does it like this, but all 4 of mine spray just fine whenever I need them to...and the reason I have 4 is that I had a production and detail gun in siphon feed for years and then upgraded to a production and detail in HVLP...Doug

Posted:
Fri Nov 17, 2006 1:28 am
by NightCap
Thanks Doug, good info. I do have a question, do I need to dilute the spar varnish? How much thinner would you put in with the varnish?

Posted:
Fri Nov 17, 2006 1:52 am
by doug hodder
check with the manufacturer...typically on the can there are instructions on thinning any product....just make sure you are spraying a solvent/oil based material...and use the recommended thinners...a water based one won't work with those type guns..others experience may vary....If you want to get really "official" a viscosity cup will help you out on the thinning...for me...I just kind of know when it is going to be thin enough based by how it drips off the stirring stick. I wouldn't use something like a straight paint thinner unless it calls for that, Xylol might be a better additive...but I certainly would check with an official paint person about the product you are using or their website, or better yet, contact their technical site. Xylol works well on oil based paints, lacquers, urethanes and other automotive products will have specific additives...and they are temperature sensitive...using a cheap lacquer thinner will be too "hot" and will flash off too quickly leaving a dry finish... Read the can, and make sure your additives are compatible with the material. Doug

Posted:
Fri Nov 17, 2006 2:21 am
by NightCap
That makes sense to me. I'll do some reading of the can. Thanks Doug, I'll let you know how my first efforts go. I of course will have to do a bunch of testing first.

Posted:
Fri Nov 17, 2006 9:57 am
by halfdome, Danny
Nightcap, Those gravity feed guns are a little tipsy to fill. I always clamp mine in my bench vise to fill it. You could build a little stand to do the same. Also the wall hanger that mine came with is not really secure if you trip on the hose, you may want to hang it on a screw eye.
Danny

Posted:
Fri Nov 17, 2006 9:03 pm
by NightCap
halfdome, Danny wrote:Nightcap, Those gravity feed guns are a little tipsy to fill. I always clamp mine in my bench vise to fill it. You could build a little stand to do the same. Also the wall hanger that mine came with is not really secure if you trip on the hose, you may want to hang it on a screw eye.
Danny
Yeah, I was wondering just how to go about filling without a mess all the time. Thanks.