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post #16 of 53 (permalink) Old 01-31-2006, 02:05 AM
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Quote:
Originally Posted by GoldCloverLeaf
Is rubbing back layers of base and clear coat before applying new layers called 'flow-coating’? I here this term used a lot with show cars but i never fully understood how it was done?

Thanks again for a fantastic post.
Vantaag, yes, it's an Australian term, I've quoted this from another Aussie forum after a quick google search.

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At that time then "snick" or sand back clear coat. This can be a little complicated to someone not familiar with this process. Sand back the entire clear coat with a 1500 sandpaper either dry on a 2.5mm orbit sander, or with a rubbing block wet. This process will smooth out any peel in the surface. Then clean and prepare surface for respraying clear. Another 2-3 coats, then bake or dry again. This process is called flow coating and gives the best clarity and depth to a pearl refinish. the extra effort pays off. When dry, the whole car car then be sanded with 2000 followed by 4000 mirkon sanding disks then buffed for the ultimate sparkle.
Whilst he's talking specifically about a pearl paint job, the same process can also be used on a more conventional finish. I think the idea is to get the finish really 'flat' and free of orange peel.

Not sure why it's called 'flow coating' except that perhaps the finish looks like the paint has 'flowed' over the surface.
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post #17 of 53 (permalink) Old 01-31-2006, 05:49 PM
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Thanks Hamish, thats what i meant by 'flow-coating'. There truly is a lot of slang in this industry that varies from country to country!

Might give this a try on my 105 when the time comes, got nothing to loose but time with this application.

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post #18 of 53 (permalink) Old 02-01-2006, 03:08 AM
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Yeah, the slang is quite a bit different. I'm by no means a professional spray painter, but I have painted 4 or 5 cars at home (naughty me ) and some of the terminology Vantaag is using is unfamiliar to me.

What Vantaag calls 'lacquer', I think we call 'acrylic lacquer' (in a weird reversal of the Australian habit of contracting the name of everything to an absolute minimum) which is still readily available in australia, and what I have used to paint cars.

It also has a few redeeming features for the home painter,

* it is relatively cheap
* it dries really quickly, so it far less troubled by dust contamination.
* it doesn't contain really toxic isocyanates, so it won't kill you outright
* it's quite 'soft' so it's easy to wet/colour sand before buffing. It is also easy to sand out runs and other amateur boo-boos. In other words, it is pretty forgiving. (this softness is also it's greatest flaw, it is nowhere near as durable as more modern 2 part finishes)
* done right, you can still get a really good shine out of it.
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post #19 of 53 (permalink) Old 02-01-2006, 08:52 AM
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Quote:
Originally Posted by Hamish
What Vantaag calls 'lacquer', I think we call 'acrylic lacquer' ...
Read Vataaj's definition of "Lacquer" and "Acrylic" again. It would appear that his "Acrylic" matches your description of "Acrylic lacquer".

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post #20 of 53 (permalink) Old 02-02-2006, 05:11 AM
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Doesn't really sound like what I call Acrylic Laquer. Unless what he is describing is what we call nitrocellulose ( which nobody uses ) and acrylic laquer is the 1 part acrylic?

Aussies seem to describe automotive paints in 3 basic categories, Acrylic laquer, air dry enamel, and 2 pack ( 2 pack covering pretty much everything that is a 2 part type paint where you add a catalyst type hardener)

But, your post perfectly illustrates the confusion caused by the variations in terminology used to describe exactly the same thing

Maybe we should get a chemist to clear up the confusion
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post #21 of 53 (permalink) Old 02-02-2006, 07:59 PM Thread Starter
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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/me...glish/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.

Last edited by Vantaaj; 02-02-2006 at 08:31 PM.
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post #22 of 53 (permalink) Old 02-02-2006, 08:29 PM
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An interesting explanation of the early development of automotive paints [and especially nitrocellulose lacquer] can be read here [click on all the key words to get the full story]:

http://heritage.dupont.com/floater/f.../floater.shtml

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post #23 of 53 (permalink) Old 02-03-2006, 11:29 AM
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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!

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post #24 of 53 (permalink) Old 02-03-2006, 03:59 PM
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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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post #25 of 53 (permalink) Old 02-03-2006, 09:20 PM Thread Starter
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Quote:
Originally Posted by Capp
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

Last edited by Vantaaj; 02-04-2006 at 06:39 AM.
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post #26 of 53 (permalink) Old 02-03-2006, 10:44 PM
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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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post #27 of 53 (permalink) Old 05-19-2006, 03:54 PM
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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.



Quote:
Originally Posted by Vantaaj
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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post #28 of 53 (permalink) Old 12-11-2006, 08:02 AM
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A lot of great info here. Good job!

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post #29 of 53 (permalink) Old 05-22-2007, 04:40 PM
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SHERWIN WILLIAMS You Paintin Your House
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post #30 of 53 (permalink) Old 05-22-2007, 06:57 PM
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Originally Posted by ga_mtn_spider View Post
SHERWIN WILLIAMS You Paintin Your House


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 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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