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Discussion Starter · #21 · (Edited)
Okay, this is a little confusing and I was not accurate in my initial post. (I have edited it to make it more clear).

What I initially referred to as "lacquer" should have been referred to as "nitrocellulose lacquer." It is illegal in most countries, but it's the paint used by the factories on almost all cars made prior to 1980. In the U.S., nitrocellulose lacquer is generally referred to as "lacquer" by most body shops and lay people.

Technically, lacquer and enamel describe the process in which a paint dries and bonds to its substrate.

Lacquer is carried in a solvent and does not cure, it only dries. The solvent simply evaporates and leaves the paint behind. This is a one part (or non catalyzed, 1K, or 1 pack) paint. The solvent used to thin the paint will disolve it after it has dried.

An enamel dries and cures. As the solvent evaporates, it undergoes a chemical reaction. Once that chemical reaction has occured the paint is less soluable. Generally, but not always, this paint is a two part (catalyzed, 2k or 2pack) paint. There are also alkyd enamels which take a long time to cure and are not catalyzed.

The salient differences between enamels and lacquers were drying time, hardness, and soluability after drying. Nowadays, these issues vary from paint to paint and less from paint type to paint type. Ask your paint supplier or body man for a recommendation or read the data sheets.

Acrylic refers to base of the paint (it's vehicle) which is a plastic. Acrylic can be either an enamel or lacquer. I generally think of Acylics as either 1K or 2K (catalyzed or not). The solvent can be petroleum or water based (aqueous acrylics). In most autmotive applications the solvent is petroleum.

There is a longer explaination by Robert Foster on Craig Central.

Hope this helps clear some things up.

Mike

PS According to Sherwin Williams' automotive website, their acrylic lacquer paints do contain isocyanates. Read the material safety data sheet at http://www.sherwin-automotive.com/media/msds/English/1074.pdf. All automotive paints are extremely dangerous. If you spray them at home, buy a forced air respirator and cover all your exposed skin.
 

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nitrocellulose laquers make for some beautiful finishes - easy to layer and hand rub, polish well. But it takes a lot of work to make them look like a good clearcoat or acrylic.

But the biggest problem is that they do ger very brittle. Wide temperature changes will crack the paint with myriad spider veins. This can happen very quickly if the paint is too thick; generally you cannot successfully paint over a previous layer without heavily sanding.

"20 coats of hanbd rubbed laquer" was the old show car finish. Sprasy on 5, sand off 4, repeat. And those old show cars would shatter if they got into the hot sun.

The modern poly's can have the sheat metal "undinged" without damaging the paint!

R
 

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paint systems

Vantaaj--
On a related topic, but perhaps best booted to another thread, is the subject of types of paint spray equipment you use/prefer. I.E.: HVLP, conventional, cup guns, pressure-feed guns, etc., and how they relate to the typical hobbyist, as most of us can be described. I have been out of the loop for a few years, but it appears that as the general trend in equip. has gone to HVLP, the materials have obviously followed, now being formulated almost expressly for that application technology. Obviously this limits what hobbyists can safely and practically accomplish at home with older equip.
I will say that I'm old enough to remember when, as an industry insider, HVLP was known as a a necessary evil, devised as a way to meet emerging emissions standards in N.Y. and California, and having nothing to do with quality finishes. The purely coincidental discovery of increased material savings (under ideal conditions) was soon discovered by marketing types and has since been accepted as gospel.
 

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Discussion Starter · #25 · (Edited)
Capp said:
Vantaaj--
On a related topic, but perhaps best booted to another thread, is the subject of types of paint spray equipment you use/prefer. I.E.: HVLP, conventional, cup guns, pressure-feed guns, etc., and how they relate to the typical hobbyist, as most of us can be described.
I don't have a lot of experience with all the different paint guns, I stick with what I like/own. I use a Sata Jet RP with a 1.3 tip for everything these days. I only use Sherwin Williams paints (I like the shop manager; that is the only reason), and their new primers all spray like base/clear. The exception to this is polyester primer and then I use a Sata KLC HVLP gun with a 2.1 tip. I have a Sata minijet 4 HVLP which I occasionally use for small things, but I don't really like it. It's spray pattern is not as nice as the RP and its too big for small touch ups. I use a Badger 150 airbrush for small detail work.

Regarding HVLP, most people are now switching to "compliant" guns (which the RP is) which have the same emissions output as the HVLP guns but they spray more like traditional guns. I don't know any automotive painters who as using pressure pots. My guns are all cup guns (even my airbrush).

I know a bunch of painters who swear by the Iwata LPH-400 (an HVLP gun). And, the Sharpe Finex guns get good reviews from people I know. This subject is discussed ad nauseum on the bulletin boards at The Autobody Store BBS. Paint guns are a religious subject for most painters. As I said, I just stick with what I know.

Given what I have been told by people I trust, I would by the Finex F300 gun for $82 if I wanted an expensive gun that would lay down paint well. Otherwise I would by a Sata RP or an Iwata LPH 400. Both are around $500. Paint guns are very personal in terms of like/dislike, your mileage may vary.

The quality of the gun has a lot to do with the quality of the final product. You cannot get good atomization from cheap guns. The modern paints are finicky. Given the cost of the materials, I would invest in a good gun. At 200-500 a gallon, you don't want to waste the paint!
Mike
 

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Thanks for clearing that up Vantaag, looks like I have been using a 1k Acrylic (lacquer). I've never seen Iso warnings on any of the 1k paint brands I've used here, only on the 2k catalysed ones, but I've always worn a mask regardless.

The alkyd enamels are the air dry type that is still sometimes used, but I've never used them - too slow drying, and the 1k acrylic (in 'solid' colours) is so much more forgiving of my ordinary equipment and technique :)

Even with my limited experience, I can concur with your comments on the amount of time required, and importance, of getting the bodywork 100% if you want the paint to look good.
 

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Vantaaj, thanks for this great info post which I am just reading for the first time. I recommend though that you clarify a couple of things in you initial post. First what you call Nitrocellulose lacquer is not what people call just lacquer in the street. Nitrocellulose lacquer hasn't been used in cars since the 1950's due to its poor durability. From that time until around 1980 the lacquer that was used is acrylic lacquer and this is what is normally referred to as lacquer in the industry. Second what you referred in your initial post as Acrylic is acrylic enamel. In a second post quoted below you went to explain the differences between lacquer and enamel but this contradicts your opening paragraph on the initial post. What I would recommend is to cut and paste your enamel vs lacquer post from below and introduce it in the first post; in addition, I would rename acrylic as acrylic enamel and Nitrocellulose lacquer as acrylic lacquer (or just lacquer). BTW the only modern use of nitrocellulose lacquer that I know is nail polish because nitrocellulose lacquer dissolves very easily in acetone.



Vantaaj said:
Technically, lacquer and enamel describe the process in which a paint dries and bonds to its substrate.
Lacquer is carried in a solvent and does not cure, it only dries. The solvent simply evaporates and leaves the paint behind. This is a one part (or non catalyzed, 1K, or 1 pack) paint. The solvent used to thin the paint will disolve it after it has dried.

An enamel dries and cures. As the solvent evaporates, it undergoes a chemical reaction. Once that chemical reaction has occured the paint is less soluable. Generally, but not always, this paint is a two part (catalyzed, 2k or 2pack) paint. There are also alkyd enamels which take a long time to cure and are not catalyzed.

The salient differences between enamels and lacquers were drying time, hardness, and soluability after drying. Nowadays, these issues vary from paint to paint and less from paint type to paint type. Ask your paint supplier or body man for a recommendation or read the data sheets.

Acrylic refers to base of the paint (it's vehicle) which is a plastic. Acrylic can be either an enamel or lacquer. I generally think of Acylics as either 1K or 2K (catalyzed or not). The solvent can be petroleum or water based (aqueous acrylics). In most autmotive applications the solvent is petroleum.
 

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SHERWIN WILLIAMS:eek::eek: You Paintin Your House:D
:D:D

Sherwin Williams is best known for house paint, but they do offer an extensive line of products. while i use PPG or Dupont automotive paint for most trade show model applications, i do use SW for their Polane paint. Super Nasty Toxic Stuff :eek::eek: won't go near it without full body suit and fresh air respirator, even for small projects. but it IS super tough. think silver paint on your cell phone or tv remote . . .

personally, i dont find two stage (clear over color) any easier to spot repair than single stage (disclaimer : i usually paint small enough things that often an entire respray is easier than a repair). i also think that single stage looks more period correct for our vintage Alfas than a clear coat finish.
 

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I like spraying bc/cc or basecoat clearcoat but let me explain if you paint your car with single stage and it is wrecked most likely the repair facility will refinish the repair with bc/cc. unless the color match is dead on they will prep for a blend into the next panel which will consist of scuff or sand then papering it off until the new or repaired panel is sufficiently base coated, once it is they paper is pulled off the blend panel allowing the base to be dusted into the blend panel, just enough to give the appearance of a perfect color match. Then the deal is sealed with clearcoat the entire panels with clear. If the repair shop refinished with single stage it can be blended but I don't consider it to be a repair to last as long as the rest of the paint. You overthin your last coat just where you are stopping the paint, I personally put hot reducer in the gun and flash a quick coat on the blend to melt it in. You can then bluff and it look great but many time it will develop a hazy streak over time. Back in the mid 80's PPG come out with Deltron and sent me to The Ford plant in Hapeville for a 2 day school. According to PPG the basecoat clearcoat set up came about to make it easier to apply metallic and pearl colors. I will tell any of you if you are thinking of painting anything with metallic in the paint and have no or limited experience go with bc/cc it makes it a lot more goof proof and if you have a problem you can correct it quickly in the basecoat. Single stage has the nasty habit of the metallic moving around in paints that sit and stay wet,that's what gives the cloudy or modeled appearance, the basecoat flashes so fast if you have a uniform pattern in your metallic it stays there.As for brand ask around in your area cause paint lines are just like hamburger joints everybody has a preference and sometimes a no name mom and pops cafe is best. I use a paint made down the road in Canton Ga. They don't sponsor a Nascar team so it is affordable and gives excellent results. In fact it is the same paint Year One puts on all their cars including the Chip Foose 69 Camaros they are building from scratch:cool:
 

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Water based?

Does anyone have experience with the water based paints that serve as a base coat for a bc/cc paint job?
 

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Would like to add another request for more informative information, and I hope I'm not jumping the tracks to much for this.

There seems to be a number of variables to painting. Temperature, moisture (humidity), solvent ratios, weakest link (1K vs 2K), this only to name a few. I was wondering if there was a simplified understanding of the causes of all the mistakes that are made? Orange Peel is caused by.... Fish eye is.... The clearcoat peel problem.... Runs.. etc?? I have the basic beginners understanding but with so many variables and some many those variables affecting each other, what is the best way to watch out for the common errors. There must be a "sweet spot" for all these variables and following the manufactures guidelines would help that, but what happens if the temperature changes, and how much of a change would greatly effect the painting process? A rise/drop of a couple degrees would effect the results by how much? a lot, not much? Can I offset that change with a fluctuation of Humidity. Eg. Hot day and low humidity? what does a hot day do to the dry time besides speeding it up. Do I change my ratios and by how much?

Not looking for the definite answer of this but if I can keep as many of the worst variables consistent then, I'm guessing, that I would have a better chance. Maybe....

Thank-you all in advance.

Ps. Will be requesting the "Spray Painting 101" 2hr DVD from Stuarts Autobody Store to learn more
 

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just wanted to say thanks for the info, that and the links realy helped with my first attempt at a base clear finish.



 

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Two stage paint issues and questions

This is my first entire painting of a car in 2 stage. I've painted numerous 2-stage wheels. My major concern, at the moment, is issues (aka bugs) in the clear coat. On the enclosed photo of an area on the front of the hood, the issue on the left is a major divot caused by partially removing a bug on the second of three coats of clear. The one on the right is an embedded bug on the final coat but goes down pretty deep (I did a bit of scratching after taking the photo).

The color is the Alfa medium silver metallic. For now the clear has been color sanded with 1000. I've spotted in (after drying) small divots in single stage paint and it works fine. I assume I can do the same with clear? Any other suggestions - short of repainting - especially if it is a sure fire way to get rid of embedded bugs?

Though it is pretty faint, I have an area on the front cowling which bothers me. If I respray the panel, I'm concerned that where I join the fenders (I cannot blend to save my life) the paint thickness will be at different levels.

Except for bugs in the clear and the tedium of spraying six coats, I really like 2-stage. I was amazed that after final polishing scratches were simply not a problem.

One more question: To get a deeper shine, do any of you spray three additional clear coats after sanding down the original three? Is it worth it?

Biba
 

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With the paint system I use (DeBeer), it is unnecessary to have more than two coats of clear, which makes it particularly good where there's a great chance of contamination.

I apply the basecoat in several thin coats, making sure the metallic pattern is consistent. Then I clean it with a tack cloth, and spray a medium-to-thin coat of clear. A thin first coat is a bit less likely to give fish-eye problems. Wait 15 minutes - the clear is usually touch-dry enough to use a tack cloth again by that point - and finally apply one, heavy, even coat to ensure the orange peel flows out. I stand by with the tweezers for a while, then I close the garage door and run away...

The second heavy coat does give a great risk of runs and fish-eyes (craters caused by silicones or other contamination, which are never a problem for the primers or basecoat and only a problem for the clear...), but at least you avoid the need for two or more layers of dust and bugs, and can get less orange peel overall.

-Alex
 

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Great writeup!
A lot of 80s-90s model cars seem to suffer from spotty clearcoat breakdown. Can they be repaired somewhat satisfactorily at home, or is that futile? What causes clearcoat problems?
I was surprised to see no answers to this one.

From experience, I think the basecoat always has to be re-painted - if only because all of the clearcoat must come off, and during the sanding, it's impossible to avoid sanding through the basecoat.

-Alex
 

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Primer & Finish coats

Greetings:

My Duetto is in the process of being repainted, as discussed in another thread here in the restoration forum.

I would like to discuss a topic more relevant to this sticky thread, so I am posting here. The thread is quite detailed, but does not cover the issue of finish painting over the various types of primer coats.

My process flow was to first get the car media blasted, then primed in epoxy, then have any relevant panel restoration done, then get the finish paint applied.

I am now faced with an unfortunate reality: the paint can't go over the previously-applied primer due to the time lag - it needs to be fully scuff sanded to allow adhesion. Even then, the finish coat will be making a mechanical bond with the primer, rather than a chemical one. On the outer body surfaces, sanding seems straight forward, but for all the other surfaces - inside the wheel wells and engine bay, it seems it would be almost impractical to scuff-sand with a high degree of success in corners, nooks and crannies.

One thought I have been having, and discussing with the shop, is to simply do another media blast and get back to metal, then do wet-on-wet primer/final. Not surprisingly, the cost of a reblast may actually be less than the $$$ for all the sanding man-hours and material.

Am I being obsessive here? Any recommendations?

- Michael
 

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Michael-
You're talking about the high build primer (possibly polyester) used after the bodywork rather than the epoxy primer, correct? Or both?
Either way, the color coat bond is primarily mechanical. You'll be able to scuff nooks and crannies with a 3M Scotchbrite or similar. I'd go over the rest of the car lightly with 600 wet on a DA. A good wash and it's ready to go.
 

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Greetings:

Thanks for the advice. 95% of the primer we are speaking of is the epoxy laid on right after the media blast back in May. There is little body work, thankfully.

After several discussions, I am planning on staying with the "mechanical" approach to moving forward, rather than re-blast and wet-on-wet. I am told that wet-on-wet primer/finish over bare metal would be a superior approach, but if anything but very minor filling is necessary, the process falls apart.



- Michael
 
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