New Problem, Paint

[ronn]

Senior Member



Join Date: May 2010
Location: Bucks Co, Pa
Posts: 2,104

Re: New Problem, Paint
Pooch, You're scaring me! How perfect does the mixing have to be? A couple of thin lines on the mixing cup more or less? Because I might be in for those "Dramas". What shape do those Dramas take? what should I look for? Oh God! Out of the frying pan into the fire! Maybe!
Terry
QUOTE=pooch;1288794]Sand the whole panel down to smooth at 800 wet finish .

Spot paint where you see primer with thin coats overlapping each coat a bit further as if you doing a spot repair.

Then blow over 3 more thin coats over entire panel.

It only takes a few more drops of thinners to thin enamels over normal consistency, so don't overdo it .

Hope you mixed the paint/hardener properly the first time....or you could have dramas.

The reason for thin coats is you don't want up to 6 full coats of finished enamel on, or a stone chip will look like the Grand Canyon.[/QUOTE]

uh oh, better get Maaco!!!!!!!!!!!!!!!!

 

[Mikeinnj]

Terry,
You still have not stated what type of paint you used on the car.

PPG Shop Line paint comes in three grades; "good" "better" and "best" quality. They also make a urethane, a single stage enamel, a base coat/clear coat system and depending on which system you used , refinishing and touch up can be significantly different. please advise us....

 

[Cool Hand Lurker]

Even with the best paint and thinner, to get rid of orange peel depends on a lot of things. Humidity, air temperature, paint temperature, surface preparation, air pressure and paint viscosity can really affect things. Nobody has mentioned viscosity yet so I will. Adding thinner "to a mark" will get you close but if you want it right you should use a viscosity cup that measures the flow properties. You pour some thinned paint into the cup and count the drips per minute coming out of the hole in the bottom of the cup. Then adjust the amount of thinner to get the recommended drip rate.
You can get one at most auto paint stores or even at Home Depot. This is what it looks like:

 

[Terry NJ]

I did not know that! Stupid me! JEA/GL Chicle Drab Code 91 2368/5% And JEA/QT copra drab code440 33006/5% can you tell anything from these numbers?
Terry

Terry,
You still have not stated what type of paint you used on the car.

PPG Shop Line paint comes in three grades; "good" "better" and "best" quality. They also make a urethane, a single stage enamel, a base coat/clear coat system and depending on which system you used , refinishing and touch up can be significantly different. please advise us....

 

[Terry NJ]

One guy showed me how to do the drip test with a paint stirrer. But who says that was right? Maybe it's wrong, but I like to put the thinner into the cone first. I believe in laboratories it always add the larger quantity to the smaller quantity. The turbulence mixes it better and you're less liable to get an unmixed blob of paint at the tip of the filter cone. Is that wrong?
Terry

Even with the best paint and thinner, to get rid of orange peel depends on a lot of things. Humidity, air temperature, paint temperature, surface preparation, air pressure and paint viscosity can really affect things. Nobody has mentioned viscosity yet so I will. Adding thinner "to a mark" will get you close but if you want it right you should use a viscosity cup that measures the flow properties. You pour some thinned paint into the cup and count the drips per minute coming out of the hole in the bottom of the cup. Then adjust the amount of thinner to get the recommended drip rate.
You can get one at most auto paint stores or even at Home Depot. This is what it looks like:

 

[tbirdtbird]

Cone?
You aren't mixing in a 1 QT scaled mixing cup where upon you can get a real good mix? At most paint shops I have ever been to they give you a couple of these cups and a couple filters and a couple mixing sticks with any paint order you buy. And they give proportionately more consumables as the quantity of paint you buy goes up....

As far as the viscosity metering cup pictured above, after you have shot a fender or two you pretty much can tell what viscosity is needed without it. And if you follow the ratios supplied by the mfg, you will be right on anyway.

As far as reducer, we have NEVER used/needed more than was specified by the mfg. If anything, sometimes less. For example, as good as PPG Concept is we cut the reducer in half when using that product o/w it has a slight tendency to run and sag. Not so with half the reducer.

 

[Cool Hand Lurker]

QUOTE=tbirdtbird;1289237]Cone?
You aren't mixing in a 1 QT scaled mixing cup where upon you can get a real good mix? At most paint shops I have ever been to they give you a couple of these cups and a couple filters and a couple mixing sticks with any paint order you buy. And they give proportionately more consumables as the quantity of paint you buy goes up....

As far as the viscosity metering cup pictured above, after you have shot a fender or two you pretty much can tell what viscosity is needed without it. And if you follow the ratios supplied by the mfg, you will be right on anyway.

As far as reducer, we have NEVER used/needed more than was specified by the mfg. If anything, sometimes less. For example, as good as PPG Concept is we cut the reducer in half when using that product o/w it has a slight tendency to run and sag. Not so with half the reducer.[/QUOTE]


Terry, that is the EXPERIENCE we were talking about. And you can do that if you paint frequently and don't forget the tricks. But it sounds like you haven't done a lot of painting. You should start out using the viscosity cup or mixing exactly as the manufacturer advises, as tbird said above. If you get a lot of experience painting in various temps and humidity then maybe you can rely on what you have learned but right now you should follow the directions on the can or use the viscosity cup directions.

At least that is what I think. I have done a lot of painting but nothing in the last 10 years and I would do a lot of practicing before I tried it again. Paints have changed too.

 

[Mikeinnj]

I did not know that! Stupid me! JEA/GL Chicle Drab Code 91 2368/5% And JEA/QT copra drab code440 33006/5% can you tell anything from these numbers?
Terry

Terry,

You are using PPG Shop Line JEA which the code for their Acrylic Enamel used with a hardener. The GL at the end of the code indicates the quantity, in this case one gallon.
The JEA/QT is the same paint in a one quart size

You could have sprayed a final clear coat instead of color sanding but that would have had to be done within so many hours of applying the color coats. Here is a link to the three different Shop Line paints available.

http://us.ppgrefinish.com/getdoc/9971a97c-1c79-4bb0-bf7b-7ce449e4e8f0/Shop-Line-System-Selection-Guide

 

[tbirdtbird]

Yikes so we were color sanding enamel with 400?

I did not think enamel ever got hard enough to sand with anything.

Urethane paints get the hardest and are the most durable and most resistant to stone chips

 

[tinman080]

After 45 years as a professional painter and auto body repairman I can tell you that your problem is the lack of experience. A machine paints 90% of a new car, so painting is not difficult. What is the mark of a good painter is the ability to deal with about any problem that might come up. After a couple of small jobs you would feel much more confident painting a whole car. I first shot acrylic enamel about 1970-71. It was a new product and everyone at the time was used to lacquer or Dulux (regular) enamel that took 2 days to dry. I build the bodies for my replica cars out of plywood, I skim the wood with a thin coat of Bondo to hide the wood grain, sand it dry with #80 grit DA paper, prime it nicely with about 3 coats of lacquer primer. Let her dry overnight and then DA again with #180 grit paper dry. Then a quick go over with a red scuff pad to get any small missed spots. Wipe it down with a enamel reducer dampened rag, let it dry and hit it with a damp H2O rag and shoot it with a light to light medium coat of paint. Let that paint flash off for about 30 minutes, this will give the succeeding coats a good ''bite'' and runs won't be a problem. Many inexperienced painters get the car too ''slick'' by wet sanding with too fine a paper while prepping the car. This can make it hard to prevent runs. For acrylic enamel #400 to #600 wet prepping is more than adequate for a nice finish. Any orange peel is best sanded with #600 grit wet. DON'T sand the peel out completely, just sand the top of the peel off and leave your pad and compound something to do. You will get a lot less thin spots doing this. A couple of pics of acrylic enamel done my way. ha The black car had 2 coats only of $45.00 a gallon acrylic enamel off eBay and the green car had 3 coats of $60.00 acrylic enamel got on eBay. Both had hardener added, recommended mix up front and finished off with a touch more hardener and enamel reducer. When buffing put the liquid compound on your pad and spread it around, then run your buffer, not too big an area. Remember a slow turning pad with fresh compound and used with medium to high pressure cuts far more rapidly than a fast pad moved quickly. However you paint the car, the best of luck!

 

[Terry NJ]

Tinman, You made such a effort on my behalf that I even turned Dagen McDowell of FBN off this AM to read your post. Looking at your pics, you're certainly getting the results. Looking at those vehicles, I have a hard time finding evidence that the bodies are wood! Bravo! And that the bodies were painted with inexpensive materials. Not some pie in the sky, super expensive paint, imported from a little mountaintop factory, staffed by former chocolate making elves, in the Swiss Alps at $300 an ounce. It's your skills, not your materials!
You are 100% correct in what you say, It Takes Experience! That sorta reminds me of the old R.E. salesmen's credo of the three most important words in R.E. are LOCATION, LOCATION, LOCATION! Here It's experience, experience, experience! I painted exactly two vehicles, no actually one, A 1965 ford Pick up truck. I was advised to use DuPont Centari (at $15 @ qt IIRC) in about 1974. and I haven't picked up a spray gun since then. Thanks for posting this! And congradulations on your two vehicles. BTW, Does Va. charge you Personal Property Tax on them? They get a little crazy I've heard. I have property in Shenandoah Co where I was going to retire to but that P.P. tax was one of the reasons we didn't.
Terry

 

[tinman080]

Terry you are too kind, my post was not to showcase my junk but to show what can be done, and not a lot of money either. Obviously if I was painting a weather exposed car that was going to be in the elements all the time I would base/clear the car with Sikkens or its equivelent. It's higher than a cat's back but it does not deteriorate once it's applied. The cheap paints are fine for cars that have 3-10 days total sun every year. On acrylic enamels there are a couple of styles of chemical makeups, and the hardeners don't always jive. Get a couple of dented fenders from a local shop. Sand them different ways and shoot different areas with different mixes and air pressures. You will find a mix and application style that you feel really comfortable with. My cars are used as parade cars and show cars. As long as they aren't registered there is no personal property tax on them. My real estate tax here is 54 cents per hundred dollars of valuation, running about 95 bucks a month, payable twice yearly. My '08 Wrangler and wife's'12 GMC and my Jon boat run less than 400 bucks a year. Not too bad, a good clean area, nice schools and folks, and the grandkids are here. lol Best of luck, Gary

 

[pooch]

OK, has been stated here your paint is a urethane enamel with hardener.

The hardener is isocyanate which basically introduces oxygen into the mix.

Old enamels before this were just air dried.

Enamel dries (cures) by oxygen from the air first of all skinning the surface and working its way down over a long time.

The hardener helps this along somewhat from the inside .

When a fresh urethane/hardener job is sanded thru to primer, it leaves a feathered edge of still softish paint which is very susceptible to frying.

This is thinners getting under the thin edge and lifting it .

If you were a bit light on hardener in the first shoot, this problem gets worse.

To be fairly sure of no frying, leave the panel out in the sun to bake as long as you can, maybe 2 weeks, it is stil a risk painting straight over again with colour, it really needs to be primed or sealed over those thin paint edges to be sure.

Personally I would just bake it and paint straight over, but shoot a dry thin coat (thin as in paint thickness, not thin as more reduced) over the sand thru areas , and then same again, and leave for at least 30 mins between coats so you don't have fresh thinners attacking those edges.

Once the first mist coats have settled and you are sure it won't fry, you then blow over the entire panel.

Again, not too wet until the very last coat.

800 wet finish is as fine as you want to go to get the paint to stick.

 

[Cool Hand Lurker]

OK, has been stated here your paint is a urethane enamel with hardener.

Pooch, I don't know if this matters but in Post #28, Mikeinnj stated: "Terry,
You are using PPG Shop Line JEA which the code for their Acrylic Enamel used with a hardener."

I did not know the details of how the hardener works so thank you for that, but does that process act different whether it is urethane or acrylic enamel?

 

[colin1928]

Terry I am not able to help or give advise just letting you know I sand through the colour also when I do paint a car which is about every 7-8 years and all I can say keep working and you will get there as others say practise and then more practise

 

[tinman080]

do paint runs go up down under?

 

[tbirdtbird]

there has been some excellent technical input but it is not clear to what degree it has been received

 

[tbirdtbird]

Pooch, excuse our ignorance, but 'frying' is not a Yank term...please clarify
thx
which begs the question, in the mother country (England of course) slash refers to a certain activity...same hold true in OZ?

 

[tinman080]

tbirdtbird I do believe it is a term for wrinkling, the sand thru edges have a tendency to wrinkle and ''lift'' on the edge. Until fully cured the enamels and polyurethane basecoats are very easily dissolved by fresh reducer in the new coat of paint. If minor, it will leave a ''bullseye'' ( a shadow outline of the sand-thru in the first paint). If major it will cause what we called in the shops ''crunch'' (wrinkling), sometimes requiring razor-blading off the wrinkled finish and starting over. Many corrections are available when dealing with this while spraying. A non-sanding sealer can be applied over the featheredge, or dusting the edge with an extremely dry covering of the base featheredge with new material(paint). If this lifts, then allowing the base to dry completely and then 1200'ing the edges and dusting again till hidden will usually work.

 

[pooch]

Yes, frying is also called crazing and sometimes wrinkling or pickling.

Although frying is the word used when a thin feathered edge lifts .

The other three terms are usually used when a whole panel does it or not confined to a feathering.

It is one of the most rotten things to happen, as you have to take all the paint off at the frying, and then it is usually easier to take it all off and start again.

Most likely, nothing abnornal will happen, and all will be fine with a fresh blow over....

Never heard the term slash used for anything other than to slash one with a knife or a machete etc.

I guess Terry has enough info from various people here now to wade thru and pick the best bits out and go try again.

This is the reason why paints have "windows" of recoat times, either you have to get fresh on fresh, or wait for it to cure and sand .

In between you have a skin on top and soft under.