HVLP Spray Question

[B_Hix]

Hi guys - I confess - I am not spraying my Comet -(yet) - this question is ref my brand X, but bear with me - I have to finish brand X in 30 days or less so I can devote my time to the Comet build with the 331 on the way =)

I am going to use a HVLP gun for the first time to spray my fenders tomorrow - I have set up the HVLP gun and tested it running some acetone through it to clean it.

I need your advice on what is occuring here - is this normal (I'm not an experienced painter)...?

Maximum input pressure to the gun is 30 psi.... I have a 50' air line, so I get some drop from tank to gun. I have the pressure out of my compressor regulated to 36 psi and that gives me 30 at the gun, which is dailed in with the pressure control knob at the base of the gun - BUT (and here is my issue)...

When I squeeze the trigger of the gun the initial blast of air seems higher than 30 psi, then it drops down after about 1 second, and stabilizes at 30 psi.

Is this normal or is my regulator fouled up? Sorry if it's a 'FNP' (freakin new painter) question, but um, I am a new painter I sprayed my cab and bed last summer with a regular ol gravity feed gun - looks great, but had overyspray allllll over my garage - so wanting to try this HVLP thing.

Thanks for your advice!

[popscomet]

You need a regulator on the gun...this will stop that 1st blast of air..although you can learn to point the gun away from the target on your 1st pull on the trigger..you can get a small regulator at the paint place or a hard ware store,most likely,whats happening is air is building(pressure) up in your hose,(more volumn=more pressure) pop

[B_Hix]

Thanks Pop - I'm using a cheapy at the gun, like the one shown at the link below - I must not have worded it well, but I do have one and I guess it's not working right >.< I'll have to hit up NAPA or Orileys and see if I can get a new one. I didnt have this issue last year with the regular (old fashioned) gun, but maybe the thing went bad.

Pop in your opinion is a HVLP gun smae, harder or easier to use? I like the low overspray aspect but as a low-skill novice I'm worried about buggering up with this new gun

http://www.paintsprayersplus.com/produc ... Gauge.html

Brad

[alans 64]

with the hvlp gun, it's low pressure but it's the volume you need. I would suggest getting as mentioned a regulator for the gun at the gun with the knob to adj pressure. pull the trigger then adjust the pressure. you need volume from the compressor. I would kick it up to 90 to 100 if you can and just regulate it at the gun. also if you don't have a good filter at the compressor I would get one of the disposable ones that go between the regulator and gun.

if your not real familiar with the gun I would practice on something else before shooting the car. make sure that on your hose that you haven't been using it for air tools that you might have put oil in the line at the compressor.

just a few suggestions I have found over the years building cars.

alan

[B_Hix]

I'm a open book - all input appreciated =) The finished part of the truck looks great but I'm worried about this HVLP approach - I'll defintely screw around before I hit the fenders to make sure I'm confortable with it.

Good input - I'll pick up a new regulator tonight.

Question still stands for you experienced folks - is HVLP any harder than old school guns, easier, more forgiving, etc? I'll be spraying Kirkers Hot Rod black - the flat (satin) black urethane (UA 70388).

[popscomet]

The only gun(cup) I ever used was a old BINKS that the RAIL-ROAD gave me when I went into the paint department way back in the 70's,20 some yrs later they gave me a new gravity cup gun,as soon as I got my 1st chance,I left it lieing on the next train headed north out of town.I did not like it. OLE pop is either old fashioned or hard headed..or both I never used a gauge at the gun,the house air was 100 and I used the thumb operated regulater on the gun and I sprayed and test / tune til I got it spraying right for me,but the best advice I can say is MIX the paint just the way the maker says and always wear your respirator and try to have good ventalation...best of luck pop

[popscomet]

The only gun(cup) I ever used was a old BINKS that the RAIL-ROAD gave me when I went into the paint department way back in the 70's,20 some yrs later they gave me a new gravity cup gun,as soon as I got my 1st chance,I left it lieing on the next train headed north out of town.I did not like it. OLE pop is either old fashioned or hard headed..or both I never used a gauge at the gun,the house air was 100 and I used the thumb operated regulater on the gun and I sprayed and test / tune til I got it spraying right for me,but the best advice I can say is MIX the paint just the way the maker says and always wear your respirator and try to have good ventalation...best of luck pop

and when you wipe down before starting to paint DON'T scrub,like your washing with soap and water...instead wipe in one direction,turn cloth over wipe in direction ,clean clean thats so important.................. pop

[B_Hix]

The only gun(cup) I ever used was a old BINKS that the RAIL-ROAD gave me when I went into the paint department way back in the 70's,20 some yrs later they gave me a new gravity cup gun,as soon as I got my 1st chance,I left it lieing on the next train headed north out of town. pop

Ha! I bet you did Pop All good advice... Will put paint to metal tomorrow with this new fangled HVLP and see how it goes - I still have ol trusty if this don;t go well I'll find a train or plane to put mine on

Thanks Pop!

Brad

[popscomet]

BRAD,it had been so many yrs since RR had closed thier paint shop,that by the time they reopened it and I went in there (at 25/26 yrs old) all the old heads were dead or retired,so I had to learn it on my own pretty much,I was like a blind dog in a MEAT house but I told my wife that I was going to master that job and be good at it,she said ---ROBERT,hard headed as you are and not one to give up or cave in under pressure,MY MONEY is on you the last 30 odd years of my caree was spent in the paint shop ,after I caught on ...I LOVE-ed it BUT if I never pick up another cup gun ,it'll be to soon last mo I had a friend re do the top on my comet(ole bertha)----getting off here now,gotta pack my stuff in my truck to leave out early in the morn ,down south going wild hog hunting this week-end ,good luck ---hollar at ya sunday night pop

[Lou's Comet]

I'm a open book - all input appreciated =) The finished part of the truck looks great but I'm worried about this HVLP approach - I'll defintely screw around before I hit the fenders to make sure I'm confortable with it.

Good input - I'll pick up a new regulator tonight.

Question still stands for you experienced folks - is HVLP any harder than old school guns, easier, more forgiving, etc? I'll be spraying Kirkers Hot Rod black - the flat (satin) black urethane (UA 70388).

The air drop sounds normal to me. I would do as Alan said and bump it up to 90 psi at the compressor if you have regulator at gun.
Acetone is very thin you will have to re-adjust the gun for the paint. .
HVLP take a lot more volume/CFM than conventional. Do you know what the CFM of the gun is?? If the compressor doesn't have enough CFM painting a whole vehicle come be a problem. But doing fenders or panels would work. If it is really small compressor might have to take breaks between parts.
Since it draws more CFM water my become a problem. Compressor running for a long time may create water in lines depending on how they are setup. I would use a dispossable decadessant (sp?) at the gun. I will try find you a link to what I use. cheap insurance.
HVLP guns also like 3/8 or bigger air hose and high volume fittings. I ran HVLP for years without but did notice difference when changing over. If you have 3/8 line and standard fittings you should be fine

I like my guns but still feel my old suction feed sharpe 75 does better. Haven't used it in years tho. I found that holding the gun a little closer helps with the HVLP
Hang some paper, and set your pattern/flow by spraying test patterns on paper. I usually get like a 9-10" wide fan hlding gun7-8" away from paper.
Adjust your volume depending on how fast you are comfortable with less volume you move slower more you move faster.

With the Kirkers Hot rod black I would do all the fenders same day. Buddy did a Bronco with it and painted everything but doors one day and did the doors next day. They didn't match paint came out of same can. and was sprayed with same gun at same settings. I think maybe temp/humidity may affect the flat/satin paints more than normal base/clear.
Here is link to the desiccant filter I use, (my spelling was off lol) the link shows them a little pricey but pretty sure I pay like $15 for 2 at local paint supply.
http://www.wayfair.com/Motorguard-Compr ... 49-OKX1107

Lou

[B_Hix]

Hi guys - POPS, good luk hunting 'em hogs - hopefully you don't end up treed - suckers got bad attitudes when surprised or cornered!

@ Lou, the gun that I am using consumes 8 cfm, and my compressor is a 8.6 @ 40 psi 33-gal unit - so it's pretty close lol.. I have to give it some time to recharge, this time I'm just going two front fenders off a 49 truck, so not a big job - the big job was last summer

I have 3/8's air line, and am running a pretty robust air filter/moisture trap and dessicant setup at the compressor. Last year when I painted the cab humidty here was well over 80% - I shoulda thought of dessicant at the gun too - I did a lot of wet sanding (humidty = orange peel) but it all smoothed out nice and the cab turned out beautiful for a rookie I do have a cheapy sears dessicant filter I could set below the regulator, so what the heck, I'll give that a go!

I picked up a new regulator at Napa last night, got it set up and it's doing it's thing (working) so I'm good there - as suggested, I'll run 90-psi out of the compressor and step it to the recommended 30 at the gun.

I always run the EXACT paint mixture recommended on the data sheets - I'm not experienced enough to know how/when to cheat (!) so no worries there !

Lou, I have seen a lot of the satin/flat black finish's and one tends to think - 'flat black - that will be easy to spray!' - NOT TRUE! I learned last year that the Kirker HR Black requires a very experienced painter to get it right - vary your spray distance too much, thickness, or flash times and what happens if you get a inconsitent result - a sheen develops - so it's hard, you have to be very consistent or otherwise you have spots or lines of shinky surrounded by flat black - it's tough stuff to get right (for me anyway).

My secret? After I saw the inconsistent coating (flat - less flat - flat - sheen) I went back and added 2 more coats (more coats = more shine) then I wet sanded it out and then hit it with 4 coats of urethane clear - shiniest black you can imagine So I"m turning flat black satin into gloss back - looks fantastic on the rear fenders.

Thanks for all the adivce guys - it wans't wasted, like I said - I'm a open book

[poboyjo65]

I'm an open book too, also a book with blank pages so I'm taking all this good advice in. but since my book has disappearing ink, I'm writing down the topics for when I give it a try. Thanks

[B_Hix]

Early thoughts -

1. HVLP is harder to adjust properly - may be because my only (limited) experience is with a HP gun. Adjustment problems led to orange peel initially, then runs.... After the damage was done I figure the adjustment out - I should have practiced more - I sprayed paper until I thought I had the gun right - but clearly I didnt read the spray pattern correctly - this process was in the HVLP instructions - but paper dont equal panel....!

2. My gun says 30 psi max input - I now know that is max, but max is NOT OPTIMAL. Found the sweet spot at ~20 psi.

3. Because of the nature of the HVLP you need to 'slow your roll' versus a high pressure gun - in other words slower left/to right motion across the item, but if you are applying too much product this can lead to runs. Too fast you get a spotty pattern - too slow you get runs. A lot of this depends on the product you are applying, activators, reduces, temp etc - that is why I should have spent some time on a practice panel as opposed to reading the pattern on a peice of paper like my gun instructions said.

It is what it is - like I said - I'm not where near pro - beginner is more appropriate and I am learning as I go - couple valuable lessons today (above) and when I spray the hood I expect that I will have a much better initial result. I'll be doing 1 more coat then will let the fenders cure all day. According to my tech data sheet I can work (wet sand) the panel after a minimum of 8 hours, so tomorrow (after about 20 hours) I'll wet sand it before clear application.

It'll be fine - just made things harder on myself, but I do this because I enjoy it and we all know there is a learning curve - sometimes mine is almost a circle, but bottom line is I 'geter done'

Brad

[B_Hix]

It's official - I hate HVLP guns. I could get close to a decent finish, but couldn't get paint to lay down right - orange peel, too thin, too thick, runs...... I varied everything to include paint mixture - long story short I have sanded down and re-sprayed a fender three times looking for improvement, testing mixtures, settings and techniques. I'm one that figures experience is the best teacher and my learning curve usually isn't (usually) that long - eventually I figure things out.

Not this stupid HVLP gun - junk, lol grrrrrrrrrrrrrrrrrrrrr

I pulled out 'ol trusty, the HP (lowes) cheapy - and nailed it the first time. Guess I will live with the extra overspray till ol'brand x is done - I'll screw around with HVLP again some day.....when the stakes aren't so high.