Painting question - high flow quick disconnects?

Hi. I'm gonna start sprayin' some paint soon. I've got all the right and required equipment - big ass compressor, air filter and dryer, nice hvlp gun. All of the air line fittings and quick disconnects were purchased from Home Depot and Lowes. Just standard stuff. I have 3/8" air lines. The internal diameter of the off the shelf quick disconnects from Depot and Lowes is 3/16". Very small, but it seems standard at those places for fittings of 1/4" NPT. Devilbiss recommends their high-flow quick disconnect fittings. Any of you using these high flow pieces? Or are you using standard hardware store connections that are not high flow? I have a gauge at the gun and in some preliminary tests with 35' of air line I had no problem maintaining 23psi. I guess cfm is the concern. My compressor is 2-stage, 5.5 hp, 240v, 80 gal, with ability to produce up to around 17cfm. I would appreciate any feedback about necessity for use of the high flow quick disconnects.

Thanks in advance.

Deluxe

 

in the last year i switched ALL of my air tools to the larger fittings. Lowes is where i had the best luck finding them. it's made a noticeable difference on tools that use a large volume of air.

 

People paint all day with the small fittings and turn out some awesome finishes but the reality is that most HVLP guns will benefit from the use of the larger fittings. Lowe's usually does have them, harbor freight is another good source. Usually they are packaged as "automotive fittings". Another thing to remember is that if you're running a smaller diameter hose then there is not much point of going to the bigger fittings, use a larger diameter hose as well for best results.

 

Man I was standing in Lowe's an hour ago looking at all the fittings trying to decide if it was worth the effort to switch over. What is the most common? They had Automotive, Industrial and Universal? I am gonna have a small fortune in fittings if I convert.

What is 3/8" airhose dia, is that the OD? I was thinking about buying 1/2" airhose and just using shorter lengths so that the inside diameter would be correct.

I just plumbed the shop in 1/2" galvanized pipe , so I don't want to shortcut now.

 

I have used both the standard size and the larger size, I will say that the more cfm the better as I seem to get a smoother finish when using the larger fitting but you will need a larger diameter hose or else the large diameter fitting will do nothing.

 

Any HVLP gun needs a minimum of a 3/8 hole going DIRECTLY into the gun ! Not a regulator on the gun which squeezes the hole back down ! I am a master certified PPG painter and have been painting since the age of 14 years old and I am now 45 . HVLP's are designed for High Volume / Low Pressure (HVLP) Most quality HVLP's have a built in air regulator right in the handle of the gun . I personally have used every brand out there and stuck with the IWATA for my show cars . If you are spraying high metallics you can litterally see the difference in atomization of the pattern as it leaves the fluid tip when you change to the smaller fittings or "CHOKE" it down with an inline regulator or cheap water trap . Use the REGULATOR on the wall just after your dryers and seperators ONLY ! Don't worry about looking at an air gauge either because depending on your viscosity of liquid , that will change constantly . Learn to watch your spray pattern ! Hold the gun up against a light and pull the trigger with fluid and adjust your pressaure until you see a full and constant pattern all the way across your pattern at wide open position . If you have too much air pressure , the fluid will be heavy on the outside of the pattern and light in the middle so keep squeezing and letting off your air pressure until you see the pattern equal out all the way through for each liquid you are squirting . Not to brag but most of my walk-away paint jobs looked like they have been cut and buffed already and that's just learning how to use your equipment not science . Ask any good painter out there and he or she will verify everything I just told you . Also , the tighter you squeeze your pattern down like say to pencil in a tighter area , the less fluid and air pressure you will need . Just put the pattern on "pencil" and leave your air pressure the same as a wide open pattern and listen to the difference . I use my normal IWATA with a 1.3 needle as my airbrush also just by knowing how to use it . I have helped the techs at the PPG training facility in Houston help teach painters that THINK they know how to use a gun and have been using them wrong for years . You squeeze an HVLP down with less than a full 3/8 hole all the way through and you are now trying to make up the difference with more air and IT DON'T WORK ! You may THINK you are getting good results but you are fighting the HVLP design all the way . I am glad to answer any questions concerning paint because that is one thing I can do and love to teach others .

 

For my two regular sized HVLP guns, I use 3/8" ID hose and some Sharpe hi-flow quick disconnects. I use a gauge at the gun temporarily to find out what the actual pressure is at the gun with the trigger pulled, and another gauge back at a regulator coming out of my big Devilbiss air dryer filter thing's outlet. I made a chart in large letters on a piece of plywood next to my air dryer: "x psi at the dryer = y psi at the gun" for a bunch of different inlet pressures. Then I remove the gauge from the gun and run the quick disconnect right to the gun and use my chart to figure out what pressure I want to run at the regulator to get the pressure I want at the gun. That's to account for the pressure drop you get in the line and through the hose fittings.

I know you should probably run the hose directly to the gun without a quick disconnect for HVLP to get maximum flow, but I like having the quick disconnect at the gun, because it allows the hose to swivel, and those Sharpe hi-flow quick disconnects don't cut down the flow too much.

For my little HVLP touch up gun, I just use the regular cheap little quick disconnects and don't seem to have any problems with them on that little gun, because it doesn't eat up as much air as the bigger HVLP guns.

The high flow fittings from some of the different paint gun fittings are not as big and bulky as the larger 3/8" fittings from Milton or copies of Milton. I tried using some 3/8" Milton fittings before on the air hose to my paint gun, and wound up going back to the hi-flow Sharpe fittings, because I didn't like the extra size and weight of the bigger 3/8" fittings.

My Sharpe fitting on the hose where it hooks up to the gun leaks when I disconnect it at the gun sometimes, so I'm not too crazy about the quality, but it does seem to flow well.

 

Don't know if this is any help, but you can increase the flow of the 1/4" fitting by porting the male connect, just giving the air a smooth entry will help, but you can also drill them a bit.

 

Don't take CamaroKid for granted because he's a FNG. He's got it nailed.
I have worked in the industry for 37 years, and for a PPG jobber for a few.
It didn't make a lot of differance when we were using high pressure syphon guns,but with a HVLP gun it is a must to do exactly what the Kid said.
Check with any paint or paint gun manufacturer.

 

Thanks for the info, Folks. Looks like I'll be heading out today during lunch to locate some high-flow disconnects.

Deluxe

 

So should I buy my connectiuons from a paint supplier .ie. Sharp, Sata etc or can I use the cheaper brands at Lowe's etc? I think the quality looks better when I look at the paint suppliers websites like Autobodydepot.com.......

Thanks for the info guys. I try and do the best I can with what I have. We're not pro painters on here, so we appreciate you veterans taking the time to let us in on trade secrets.

 

You guys interested in putting on a HAMB paint training day? I would pay to go, if it's somewhere within a days drive.

 

IMHO the ones at lowes, kobalt brand i believe, are pretty good quaility, light years ahead of the cheap 1/4" fittings. NONE of my larger 3/8 couplers leak. amazing.

 

fwiw; i have no idea whether flow rates compare or not, BUT the ones i have from lowes don't leak and connect/disconnect "normally." the ones i have bought at HF sometimes leak and sometimes are hard to disconnect.

 

I have the High Flow Devilbiss on all my lines that I use for spraying and the Milton's through out the rest of my shop . I allso have the larger Devilbiss "Clean Air" system outside of my booth due to the fact that I always wet my booth down before painting and I ran a 1/2" galv. pipe directly into the booth with the Devilbiss regulator that came with the dryer system . I use the Devilbiss "Female" fitting directly screwed to all my HVLP guns and thier main disconnect on the Devilbiss air hose inside the booth . Keep that disconnect CLEAN and NEVR just drop it to the ground like you see most people do and it just snaps right into place when you are hooking it back on your gun after filling your cup back up . Throwing a fitting down on the concrete ruins the fittings ! I treat my air hose and fittings inside my booth just like my paint guns ( clean at all times ! ) It's a fact that most trash in a paint job's finish is created by YOU also ( speaking of jobs done in a booth only of course ) . When you are sanding or wiping a car down , you create static electricity . When you walk up to that car to start spraying , anything that you have on you such as dust particles , loose hair , etc, etc, is going to suck to that car like a magnet ! Some booths have ground straps to discharge the body and yes fiberglass can have static build up also . Cleanliness is GODLINESS inside a booth or even in a shop with the floor wet down and tool boxes covered with plastic ( been there too ) . Just try to keep all your buddies that just can't seem to wait for the car to dry to look at it as far away from the car with thier beer cans as possible ! If you are fortunate enough to have a booth , try not to step in your booths air-flow direction any more than you have to . Remember that anything that comes off of you will land in the finish . I personally pressure wash the living crap out of any car BEFORE it goes in my booth and I'm even talking Insurance work as well . If you are spraying along the bottom edges of a car that's filthy underneath no matter how clean the surface is that you are painting , you are now litterally blowing dirt from under the car right into your booths atmosphere ! Where do you think it's going to land ? Down-draft booths are nicer and more user friendly but unless you have a bunch of money backing you , most don't have one anyway . Hope I helped some of you guys out . I'm 45 years old and have been around the block more than a few times and just trying to help those that don't know or would like to learn . Thanks for reading , Jerry

 

Thanks Jerry.

I don't have a booth persay. Just an area that I use to keep all of the dust etc out of the rest of the shop. I usually hafta start cleaning about a week before I paint.

 

+1, I'll come out from so cal

 

Here's another question for ya......

What kind of airhose is best? I have seen rubber, pvc and other various makes.

 

Sounds like the clinic should be at Jerry's place. Frank

 

I went to a 4 hour clinic one time put on by HOK and it was informative. It wasn't a "hands on" course but it was fairly inexpensive and it was helpful to those that don't paint everday for a living.

 

Look for a hose that's very flexible and limp feeling. You want a hose that just sort of flops on the ground instead of trying to spring into a big coiled up tangle of spaghetti. It sucks trying to fight a springy stiff hose while you're spraying, especially a hose that likes to get tangled into curly cue shapes instead of lying flat on the floor. Some of the PVC hoses tend to be too stiff and springy and get looped up and tangled too easily, especially if it's a cold day. The colder the day, the more stiffer the hose gets. I have a bunch of different hoses, but I think the hose that I use only for painting is made of rubber or some kind of synthetic rubber. It's red and has a dull texture (it's not shiny). It has nylon braid reinforcing and it's rated 300 psi I think, and it's 3/8" ID. It's a little heavy, but it's nice and limp and lies on the ground nice.

When I get ready to paint something, I unroll the whole hose in a straight line and let it lie there in the sun at least a few hours. That seems to help keep it from trying to coil up on you while you're painting.

 

I bought yellow Goodyear 3/8" i.d. rubber hose off eBay. It is very good. It is like what 'Rustybolts' described.

 

I was thinking of having some shorter hoses made at a hose shop. Like 2 15 footers. One for each side of the booth.

 

My booth is 20'x30' and I use the Devilbiss hose . Rustybolts is correct about a stiff hose that tries to curl up on you . I stretch mine all the way out before I spray and have several waterhose holders ( steel ones) on both sides of my booth so I don't have to lay the first 6 feet that is closest to the gun down in the water or wet ground . I wipe the hose with lacquer thinner and tack rag it each time I fill my cup back up before I start shooting again also . Be surprised by the amount of trash that a nasty hose can cause in a paint job that was just picked back up from a booth floor and not wiped down . PS. keep a seperate tack rag for the hose than the one you are using on the car ! If you wet your floor down , also be careful not to jerk the hose around trying to get it un-lodged from under a tire or whatever because it may sling water up on the car when it comes loose from whatever it was caught on ! I really do love and enjoy answering any of your questions guys so never think you are asking too many , Jerry

 

Another little trick of the trade guys . Say you are spraying a high metallic color and you have the car coated and now you need to give the paint it's normal "flash time" before your next coat because this is the critical time that the paint needs to flash off the solvents that are used to thin the topcoats out but you still have plenty of paint left in your gun so what do you do ? Most guys will say " I just hang it up in my gun holder dummy and wait my 15 minutes or whatever your flash time is according to your application " . Here's the problem that alot of guys never think about . Metallic settles because it's heavier than liquid so it goes to the bottom of your cup . You plug that gun back in and start spraying after your flash time has passed and what happens ? Your first few passes now has a buttload of metallic comming out because it has settled downward for 15 minutes which is now lightening the panel that it's being applied on and all the rest of that cup will be darker because the metallic ratio has now changed drastically ! Some guys say I just stir it back up with a stirstick before I shoot . A stirstick does NOT get to all the metallic settled down deep in the fluid nozzle area ! POUR your extra paint back out in your mixing cups EVERY time you are waiting for your next coat time ! Also use a clock for that "flash time" and don't stand inside that booth waiting because believe me , 5 minutes seems like 15 when you have a gun in your hand and it never hurts to give base clear a little extra time anyway between coats and don't be afraid to tack rag in between bases either . If you feel a nib in the base , that's the time to get it out before you lay the clear on . Hope this helps some of you guys that are trying to learn , Jerry

 

thanks for all the tips jerry.theres alot of good info that most of us probably never thought of.

 

You are very welcome ! If you guys have any questions at all that you think I may be able to answer , please do not hesitate to ask . There is no such thing as a stupid or too small of a question in my book if you need an answer . What others take for granted from years of doing it need to realize that there are guys and gals out there that are still in a learning curve or just want to know the answers in case they may need them later . If you are trying to choose a good bodyshop and painter for your ride , some of these things may just be good questions to ask to see what thier response is . This dang paint and material is just waaay too expensive in this day and time not to ask questions and have to re-paint something . I just lost my beloved son just before Christmas on Dec. 20th that had just turned 20 years old on Nov. 22nd and this is really helping me just chatting with others and giving more of myself to those that may need what I can give .I am not a rich man and my shop is struggling with the lack of good help but I still have my self respect and some knowledge that I can share with others in need . Maybe God led me to this site the other night , who knows for sure ? Not looking for sympothy , just helps to talk with people about things that I may help them with .Don't have that many true friends really because most of them only love you when they need a shop or a paint job but I have noticed a bunch of other very giving people on here and that makes me happy in itself just being a small part of it . Thanks again for appreciating what little I have shared , Jerry

 

I'm really sorry to hear about your son. My sympathies to you and your family.

I'm just an amateur painter, but I enjoy learning anything I can about painting so I can do the best job I can and be proud of it when I'm done. Tips from someone like you with many years of experience can really help all of us out a lot. It's obvious you really know what you're talking about and your advice is all great.

One question I've been worrying about is what's the best way to sand out some small runs in clearcoat. I did a candy job, and after five coats of candy and three coats of clear, I sanded the whole truck down with 800 grit to smooth it out and get rid of the orange peel and then did 2 more coats of clear. I got some runs in the clear under the windshield on a vertical flat area where I piled the clear on too heavy. I want to sand those runs down, but I'm scared I might cut into the candy if I overdo it. What grit would you use to get rid of the runs, and what sort of backing pad would you use for a job like that? Would it make sense to try to sand just the runs separately first to level it out a little and then start using the pad? I was thinking of wet sanding using a soft "motorgard" type rubber pad (the kind that's grey on one side and black on the other) with 800, then 1000, 1500, and maybe 2000 and then buffing it. Is that about right? It's HOK candy with HOK clear. The paint is about 4 months old already.

Thanks

 

House Of Kolors clear is THIN ! And I mean THIN compared to any other brand of "high build" clears out there . I've been doing it for so long , getting a run out without going through can be a royal pain in the azz so don't feel bad at all . Depending on how much room you have with the flat area where the run is located , I actually use a piece of flat aluminum from and old PPG stirstick from back in the day , and stay just on the run itself with 600 grit at first . If the clear is that old , spray some offsetting color directly over the run area just as you would as a "guide coat" used for final wet sanding . This will let you know where you are at . GO SLOW ! This is NOT THE TIME to rush anything ! Any painter that says he or she doesn't get runs in clear is either lying or they are scared to lay some clear and probably dry spray or orange peel every job ! Just watch when the run starts getting flat and GET AWAY with the 600 ! I then use the same flat surface and keep going with 1500 until I'm where I want to be . I would rather use brains and muscle effort , than have to re-do a candy job ! Maguieres (spelling? ) does have 1000 and 1500 grit blocks out there for runs as well as small run files . I have used razor blades holding the blade straight over the run and lightly shaved the run away until it was flat . I'm not talking about laying the razor flat on the paint surface and cutting the run off , actually shaving the run ever so lightly . Now that one is kinda tricky ! You can always lay some more clear if it's in a good blendable area until you feel safe ? That may be an option . I have hit clear with 600 and blended fresh clear right to the edge of my 600 sanding and I don't care how close you looked at it , you could never see the repair . Just remember that you only have 2 types of adhesion , mechanical ( sanding ) and chemical adhesion and once urethane sets up past your time envelope of re-coating , there is no more chemical bonding ! I've seen painters let thier basecoat sit for days before they clear the car and wonder why the customer comes back with more clear on the walls at the local pressure wash than he has left on the car ! Not to brag but I envite all my customers to take thier cars to the pressure wash after 90 days and see if they can get it to flake . Now anybody can get a rock chip and put a pressure wash wand right up to the chip if you're an idiot just looking to piss your painter off ! 90% of a good paint job is prep work . I can take just about any of you guys as long as you have a high enough IQ level to blow your nose without getting it all over you and teach you to lay slick paint in no time . It's all the work BEFORE it get's in the booth that determines how it's gonna look and hold up for years to come . Hope I didn't go too far just about a run question , Jerry

 

Another note to you . I consider 800 grit paper too fine to re-coat over unless it's lacquer or enamel where you still have a chemical bond available . On base/clear , the finest I use is 600 for metallics and use small circular motions in case I need to blend in some base somewhere . The reason for sanding in circular motions is that high metallics will actually follow your "sand scratch" if you use straight motions and you will notice it when sunlight hits the car .You will actually see where the metallic laid in the straight sanded areas. Of course you use straight motions when blocking a body but we are talking final finishing here with sponge pads being used . My theory is the deeper you can scratch that surface and get that new topcoat deeper in , the more adhesion you are going to achieve . 600 is about as course as you can go without getting "shrink back" scratches later on down the line . I also do not believe in too much film thickness . People think that the more clear you put on a car , the deeper it looks ? WRONG ! It's the way the paint is laid on the car that determines depth and a darker color always looks deeper than a lighter color no matter how slick the finish is .You need just enough clear left on the cars finish after the cut-n-buff for ultraviolet ray protection . Enough for now , It's 1:35am here in Texas and time for bed ! Talk to you all soon I hope , Jerry