Author Topic: A few questions for the experts from one who has never painted a vehicle before  (Read 7770 times)

Offline got2haul

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1.  HVLP vs LVHP?  Which to use on an auto body?  Is one gravity-fed and the other siphoned, or can either be either?  Preferences?
2.  In-line dryer.  I have a 150 psi compressor but have never used an in-line dryer.  I would imagine it is necessary.  What are your recommendations?
3.  Is filtering the paint necessary?  I see this being done on the automotive television shows such as Muscle Car and Trucks, so it appears to be important.  What paint contaminants are being filtered out?
4.  Is manual thinning of the paint required, or should it be good to go right out of the can?
5.  Is drying time equivalent to that of spray cans?
6.  Anything other pointers (besides the obvious about prepping the surface)?

Thanks!
1980 Custom Deluxe Stepside
        Stepside thread: http://forum.73-87chevytrucks.com/smforum/index.php?topic=7505.0
1980 Silverado Short Bed Fleetside
1976 GMC Sierra Grande C15

Offline HAULIN IT

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Will be glad to help! You'll have to answer a few questions for the best advice...we'll get to those in a minute.
 1) I would suggest a gravity gun for you for several reasons. You can use all of the mixed product, less air required, ect. Not all gravity guns are HVLP though, but no need to confuse the issue.
 2) Yes, you want an in-line dryer & filter set-up of some sort. How elaborate/costly you get depends on your real goals of the job & how often you plan to spray paint products. More on that later.
 3) Yes, you need to strain the paint. Lots of little particales of dried paint (from the mixing lids), clumps of flattener/metallic/pearl may be in there, also a sliver off of a wooden stir stick, ect. ect. all can foul you up.
 4) Most (any that I've ever used) have some other products (thinner, catalyst of some sort) that you need to add before spraying.
 5) Most automotive paint takes longer to dry than spray cans.
 6) Pointer...Lots of them, we can talk all day & you still will have something else pop up.
 Now the questions:
 1) What color are you going to paint the truck?
 2) What is disassembled from the truck?
 3) Can you sandblast or use a sander until you get tired before your compressor runs low on air?
 4) Realistically how much money do you have/want to spend on this part of the job?
 Answer these & we can contine...You will find bodywork is like many things, MANY different opinions on what products to use & how to do it. Will be glad to help, Lorne

Offline Captkaos

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I have 2 side questions, I can split them out Got2Haul if you want me to...

What about painter opinions on Auto Air Colors?  http://www.autoaircolors.com/

What are the painters opinion on Duplicolors Paint Shop?  http://www.duplicolor.com/products/paintshop.html
It know it is lacquer based, they say there is no recoat window on it, but it is limited on the color choices, but...

Offline zieg85

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Not a car refinish expert by any means however LVLP is a great way to go.  I have been in the paint buisness for just shy of 25 years.  My division sells to the OEM and when not mandated by permits LVLP is the prefered way and saves every bit as HVLP paint wise and uses approx 50%  less of compressed air.  I have done side by side studies using high solids epoxies and 2K urethanes.
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline Donut

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I'm far cry from a painter, but this info helped me out a bunch. http://www.autobody101.com/articles/

This post is my opinions only, I've only painted 1 vehicle and it's not that great, but a year later and the rust isn't popping through.

1) HVLP, I used a siphon gun (conventional) and there was a lot of waste and overspray.  I did purchase a cheap HVLP for the repaint that hasn't happened yet.  LVLP, don't know. 

2)Some sort of a dryer/filter setup.  The separator on my compressor didn't grab much water, but I ran 1 air line overhead and added another separator at the end of that, that one grabbed a bunch of water.  I also ran a canister filter on the gun. (recommended by the paint shop)

3) Strain the paint.  One little particle could ruin your whole day. (esp. if it clogs your gun)  Strainers are cheap.  IIRC, I think they gave me a stack when I bought my paint.

4) Depends on the paint.  If your using automotive paint there should be a formula for how much paint, reducer, hardener.  IIRC you "should" get a sheet that tells you all that.  Tractor paint, you could be on your own.

5) drying time- should be covered in the paint sheet.  This will also depend on the paint used.  Even my spray cans of Rustoleum recommend 24 hrs.

Other pointers, a lot of reading and questions (and what everybody else pointed out.)
Another pointer.  I believe it was recommended here. Whatever you decide for paint, try to get it locally.  The guy behind the paint counter helped me a bunch, with pointers, what would work with what, and odds and ends that I had forgotten or didn't consider.  (great help for a first-timer)  That's something you lose over the internet.

Capt. I can't help you out, you probably know more about paint than I do.  That's a big "but" after the Duplicolor, what are you trying to accomplish?
« Last Edit: October 09, 2009, 07:58:30 am by Donut »
'73 Chevy K-20 ***SOLD***
350/tbh350/np205
My plow was half price if i took the truck with it.

'86 C-30 dually, 454/tbh400

Offline got2haul

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Now the questions:
 1) What color are you going to paint the truck?
 2) What is disassembled from the truck?
 3) Can you sandblast or use a sander until you get tired before your compressor runs low on air?
 4) Realistically how much money do you have/want to spend on this part of the job?
 Answer these & we can contine...You will find bodywork is like many things, MANY different opinions on what products to use & how to do it. Will be glad to help, Lorne

1.  I'm going to do the body work myself and paint the truck its original color -- I believe it's called Nordic Blue (This is for my 1980 fleetside).

2.  Since I don't have a paint booth, I plan to paint the truck a piece at a time outdoors under cover (carport).  The bed will be entirely disassembled (using the used replacement bed I bought recently and some of the original bed).  I will paint the front fenders and hood individually.  The cab and doors will be done as one unit.  The paint in the interior of the cab looks OK for my purposes.

3.  My compressor has a 33 gal tank.  It fills to 145-150 psi before shutting off.  I didn't look up its duty cycle, but it starts and refills once the air pressure gets down to about 100-105 psi or so.  as I mentioned earlier, I do not have a dryer/filter/separator.  Based on the information I'm providing, could someone make a recommendation on brand/type?

4.  As with anyone, I want to avoid dropping a ton of cash here.  I'm hoping for a "10-footer" paint job.  It doesn't have to be show quality, but I plan to do it the best I can on my budget.  Certainly I'd like to be proud of it (as my first attempt.)  I plan to use the tools I have on hand and maybe buy some specialty tools for prep, if I think they'll be necessary for certain problem areas I may encounter.

I plan to tackle painting the parts of the bed and reassembling it this fall.  The results of that effort will determine how quickly the rest of the job gets done.

And BTW, thanks to those that have replied with various links of informative information.
« Last Edit: October 07, 2009, 01:44:58 pm by got2haul »
1980 Custom Deluxe Stepside
        Stepside thread: http://forum.73-87chevytrucks.com/smforum/index.php?topic=7505.0
1980 Silverado Short Bed Fleetside
1976 GMC Sierra Grande C15

Offline HAULIN IT

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Chris, Here is a couple tin panels I did with AutoAirColor paint at an airbrush clinic hosted by Mickey Harris. For the last several years he has endorsed their company (been on their payroll ;)) going around the country putting on seminars for them...It's a "must see & do" for anyone, he is a REAL good teacher & entertainer.
 For airbrush work it is real nice (dries fast & doesn't tape track).
 I had my painter clearcoat the panels the next day while he was doing a car. The clear "died back" (slightly dull & grainy) quite a bit, unlike our normal basecoat even though they said it could be top coated with any urethane clear. Because of this I honestly wouldn't use it as a regular basecoat for an entire vehicle, allthough waterbase is "the next big thing" in refinishing & soon everybody will be spraying with water. Like anything else, it will be a learning curve (insert BIG in there somewhere ;D
 
Got2haul, Ok,
 1) I'm unfamiliar with the name, but I'm guessing it's that medium Metallic Blue that was on many of those trucks? Will it have a White roof? For the Blue, you will want to use a basecoat/clearcoat system.
 2) I'm all for you painting it in pieces, however with that is some VERY important steps you MUST do to end up with a nice, proper looking truck...They are as follows:  Buy PLENTY of paint (how much depends on the brand/type you chose), stir each can, get an extra gallon can, pour some in it...mix with the other can, ect. End up with ALL one color, regardless if the mix boy fouled up one  a little or not.
You need to hang the panels the way they will be on the truck (as in, the fenders need to be across, not hanging by the headlamp area or something). You want to spray the basecoat on the inside of the fenders, ect. before the outside, each time on the first couple coats, once the inside is covered...let it all dry, put another couple coats only on the outside, spraying well past the ends of the panel (a foot or so) as if there was a panel next to it.  You want to be as much of it in similar temp. ect. as possible. Get it all ready & paint for a few days if similar, not a month & a half apart. STIR THE PAINT VERY WELL EVERY TIME YOU GO TO POUR! Pour the paint you have left in the gun cup between each coat & pour it in with the next batch you mix.
 3) Painting in pieces will help with your air needs some. My concern isn't with pressure, it's the "recovery time" it takes once the compressor comes on (as in, Does it fill back up while your still spraying & shut off or does it contine to run & barely keep up to your needs? Max. pressure or tank size has nothing to do with this, only pump cfm. does). As for the drier/separator, as mentioned you should get some hose (20ft. or so) away from the tank (preferably overhead & then drop down to the catch & then more hose.
That's all for now...Let it soak in, then we can talk some more. Lorne
 

Offline Captkaos

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I ask about Auto Air out of curiosity.  Hills Hot Rod have been painting a lot of their 73-87's with it.  I don't think it would be good in a outside enviroment, but I was thinking it was more environmentally friendly.

Offline Jim Rockford

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There is a good body section on hotrodders.com

http://www.hotrodders.com/forum/body-exterior/
1973 k20 Camper special
1980 k20 custom deluxe
2004 Crown Vic LX sport

Offline 83k1500

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I have done a few paint jobs... here's what I have learned...

PREP is everything. If you do not take your time and do things right, your wasting your time and money.
Read the tech sheets that come with the paint. Use them as a basis for setting up your gun.
Use a QUALITY HLVP gun. Trust me it MATTERS.

As far as the actual spraying, it varies from paint to paint and region to region and the weather is a major pain if not in a sealed and heated booth.

You want a flat sheet of metal to test spray settings on. You want to test your natural motion with the gun with how the paint is applied, and match the two up. The last thing you want to do is go against your natural movements while painting, you will get uneven results every time.

The way I do mine is very lite coverage that I can spray over and over again continuously and not really run the risk of getting runs. I can basically avoid flash times doing this. I can only stop to mix more paint and go right back to spraying and the entire job cures at once with few defects.

When spraying anything with metallic your last spraying should be at least a foot from the surface and barely a mist that reaches the panel. This is to make the metallic even.

My opinion on duplicolor paintshop is I do not like it at all. I do not have a problem with the spraying or application, it sprayed very well. It is the forced after working that all lacquers require. You HAVE to color sand them, and you HAVE to polish them to get a good shine. It is just how lacquers are. I do like how hard they are, but that again is a plus/minus depending on how you look at it.
I did one test panel with the paint and vowed never to use it again after all the post work required.

A very easy way to set up a proper HLVP gun with varied settings...
Set you line pressure (from your compressor) to 40-50 PSI.
On the gun put the fan pattern all the way in, and the needle seat all the way in with the gun pressure adjuster all the way closed.
Start by adding two turns to everything.
This will allow pressure in, paint to flow and give you a very tight spray pattern.
Spray your test panel.
Your looking to get a 7-10 inch tall rectangular in shape that is 2 or so inches wide while spraying 8 inches away from the panel without getting runs.
If you are seeing too much paint 'bounce off' the panel, cut back the gun pressure.
If you are getting runs, cut back (turn in) the needle seat adjustment.
The fan pattern is pretty self explainatory.

Once you find setting that work for you, DO NOT TOUCH them unless you HAVE to. Weather and temp plays a big part in painting in just regular garages. You want at least 55+* and as low humidity as you can get before you paint anything.