Subject: Re: Paint questions: bare metal prep, clear-coat for lacquer?

From: [email-masked] (Harry Phinney)
Date: Tue, 31 Aug 1993 19:48:46 GMT

Wayne Smith ([email-masked]) wrote:
: The primer recommends a metal-prep, and the DU-Pont stuff that I've
: got smells like isopropyl alchohol, and it's not cheap ($15 for a pint).
: You're supposed to wipe it on and let it flash off, then you're ready to
: prime.

: Is this stuff really alchohol?  Is there a cheap metal-prep alternative?
: Should I be using something else?

DuPont Metal Conditioner's primary active ingredient is phosphoric acid,
which is a much better choice than the muriatic acid you are currently
using.  Phosphoric acid will "eat" rust faster than it "eats" good
steel, and it leaves a coating of iron phosphate which adheres well,
providing a bit of additional corrosion resistance.  The muriatic (i.e.
hydrochloric) acid you are using attacks the iron at approximately the
same rate as it attacks the rust, and the resulting iron chloride does
not adhere to the surface, leaving bare steel which readily rusts.

: I'm using acrylic lacquer (it's a little cheaper than enamel and it drys
: faster).  Is there such a thing as a clear coat for this?

Clear acrylic lacquer is available, or you could clear coat with an
enamel or polyurethane enamel (warning:  toxic!).  You can generally put
an enamel down on top of a lacquer, but putting lacquer on top of an
enamel will not work.

: Also, is there anything wrong with *not* sanding the primer prior to 
: applying the acrylic lacquer?

The primary thing wrong with not sanding the primer is that you'll end
up with a rougher finish on the color coats.

Harry Phinney   [email-masked]

---

From: [email-masked] (Bill Kish)
Date: Wed, 1 Sep 1993 14:17:27 GMT

In article <[email-masked]>,
[email-masked] (Wayne Smith) writes:
|> I'm painting some car sheet-metal parts, with most of the paint taken
|> off (ie down to bare metal).  I then brush on some muriatic acid and
|> rinse with lots of water, then dry immediately.
|> 

   I agree with harry@hp on this one, muriatic acid is a good prep for
copper or 
   zinc, it is no good for steel!

|> The primer recommends a metal-prep, and the DU-Pont stuff that I've
|> got smells like isopropyl alchohol, and it's not cheap ($15 for a pint).
|> You're supposed to wipe it on and let it flash off, then you're ready to
|> prime.

   This is the best stuff on the market IMHO, it reduces the incidence
of flash-rusting
   that is so common with water rinse products (So long as you use it on
a dry day).
   I like to apply it with a spray bottle, this avoids lint from your
rag as well as
   possible surface contamination. It's always a good idea to prime as soon as 
   you can.

|> 
|> Is this stuff really alchohol?  Is there a cheap metal-prep alternative?
|> Should I be using something else?
|> 
|> I'm using acrylic lacquer (it's a little cheaper than enamel and it drys
|> faster).  Is there such a thing as a clear coat for this?  Is there
|> anything I can use to improve the gloss (short of applying 40 coats?)
|> (These are under-hood body parts, and are quite irregular, so I don't
|> want to sand between coats).

   There are various clear coats available for acrylic lacquer,
including acrylic
   lacquer clear (still need multiple coats) and Urethane clear (hard to
work with).
   For under-hood parts, I would consider enamel instead of lacquer though.

|> 
|> Also, is there anything wrong with *not* sanding the primer prior to 
|> applying the acrylic lacquer?

   Results in a dirty looking finish. It's not so tough to sand
irregular parts,
   use 320 - 400 grit wet/dry paper, crumple it up to make it flexible,
don't use
   a block. for really tight areas, use some Scotchbrite.

			-BK

|> -Wayne-

---

From: [email-masked] (Chuck Lampman)
Date: Wed, 01 Sep 1993 14:22:34 -0500

In article <[email-masked]>,
[email-masked] (Wayne Smith) wrote:
 
> The primer recommends a metal-prep, and the DU-Pont stuff that I've
> got smells like isopropyl alchohol, and it's not cheap ($15 for a pint).
> You're supposed to wipe it on and let it flash off, then you're ready to
> prime.

I agree with the others on phosphoric vs muriatic acid- The DuPont 
metal prep solution will lightly etch good metal for good paint 
adhesion, but won't eat it away or cause hydrogen embrittlement like 
hydrochloric acid can. The instructions typically require that you not 
let the stuff dry on the metal, it makes a mess that can't be painted 
over and is difficult to remove. I use a squirt bottle, keeping the 
surface wet for about 10 minutes, then either a) rinse with very hot 
water and blow out the cracks with air, or b) rinse with water and blow 
dry all over with lots of air. Drying with a rag tends to leave bits of 
rag stuck on the rough surface, and they come back to haunt you in 
the paint.
> 
> I'm using acrylic lacquer (it's a little cheaper than enamel and it drys
> faster).  Is there such a thing as a clear coat for this?  Is there
> anything I can use to improve the gloss (short of applying 40 coats?)

Probably the best way to get a shine without buffing is to use a clear 
isocyanate enamel over the lacquer, after the lacquer has cured 30 
days to lose all of its solvent vapors. The problem with this is that 
you then have to use this approach to the whole car. Since painting 
lacquer over enamel will likt the enamel, you'll have a hell of a time 
painting the outside of the car in lacquer without lifting the edges of 
the enamel under the hood where the painted surfaces meet. another 
problem is that, unless you have a very good, filtered booth, you'll 
wind up with dust and trash in the clearcoat that you can't just sand 
out and buff.

The second best way to get a shine is to do the job in acrylic lacquer 
as planned, using only enough color coat to get a good cover, then coat 
with a full wet coat of acrylic clear lacquer; be sure to allow the 
proper flash-off time between coats. Then spray a coat of the clear 
mixed with thinner that is one temp range hotter (slower drying) 
than conditions indicate. This will take a lot longer to flash off, and 
will run more easily, so be careful. The extra flow-out time will 
give considerably more gloss than the other coats, but it still 
isn't going to look like enamel.

> (These are under-hood body parts, and are quite irregular, so I don't
> want to sand between coats).

Try it, it's not difficult, just time consuming. No pain, no gain.
 
> Also, is there anything wrong with *not* sanding the primer prior to 
> applying the acrylic lacquer?

Other than the fact that the inevitable primer overspray and trash 
and garbage stuck in the primer will show through, and the fact 
that the lacquer may not stick to the primer for lack of tooth, why 
there's nothing at all wrong without not sanding! :-)

-- 
Chuck Lampman

---

From: [email-masked] (Ed Campbell)
Date: Fri, 03 Sep 1993 18:56:41 GMT

In article <[email-masked]> [email-masked] (Wayne Smith) writes:
>Is this stuff really alchohol?  Is there a cheap metal-prep alternative?
>Should I be using something else?

	It probably is at least mostly alcohol. The difference that they
are charging you for is that it doesn't leave any deposits behind, while
the cheap drugstore variety does.

>want to sand between coats).

	I have seen clear coat for this, although the EPA may soon have
everyone using water colors to paint their cars.

>applying the acrylic lacquer?

	Not as long as there is not a long delay between painting. Sanding
removes oxides, so it should be done if you are dong one stage each weekend.
But, the final finish is usually smoother with fewer coats of paint if you
sand the primer smooth.

Ed Campbell

---

From: [email-masked] ()
Date: Sat, 4 Sep 1993 06:31:41 GMT

>the cheap drugstore variety does.

Quick question for a confused person (me):
Is Du-Pont's kiwk-prep all I need to prep bare metal for priming or should I
also use another metal-prep in addition to this?

Normally I wouldn't even bother with metal prep (just sandblast and paint ...
has been pretty reliable so far) but recently I did some work on my car and
only used Du-Pont's kwik-prep.  In the future should I do what I have been
doing (use only kwik prep) or should I use another metal prep in addition to
it?

I do have another brand (don't know what it is .. it is probably hidden
somewhere in the garage) where you pour it on the metal and wash it off with
water then dry.  I think this stuff may have been mentioned in a previous
article.

Is it okay to use either or should I be using both?

---

From: [email-masked] (Wayne Smith)
Date: Tue, 7 Sep 1993 01:15:48 GMT

>also use another metal-prep in addition to this?

I did lots of (manual) labor this weekend...

Yes, the Dupont Quick Prep is mostly alchohol  (the dam fine print...)
As far as I can tell, the stuff should really be called a surface cleaner
(ie drag a clean rag soaked with this stuff over the surface to remove
dust, etc) and then it flashes off without rusting the surface.

My advice is not to waste your money on this stuff.  Use an air gun,
or even rubbing alchohol (it can't be that bad).  It the paint jobber
can't tell you why Dupont's Quick Prep is better, or different, than 
drug store alchohol, then he doesn't deserve $15 for a measely pint.

>doing (use only kwik prep) or should I use another metal prep in addition to

I had some old Adchem (sp?) stuff.  They make a line of metal treatment
stuff (for zinc, aluminum, etc).  They have 2 different products for
steel, which seems a little like the -shampoo and conditioner- 
commercials.  Both of them contain phosphoric acid (with no other
ingredients listed).

I sandblasted my stuff, but then I brushed on some HCl, and I noticed a
*big* difference in how the surface looked (the acid treatment looked
brighter).  The phosphoric acid treatment (Adchem) also made the surface
look brighter.  I had problems with the rince though- unless I was very
fast to dry the metal off after rinsing it would rust and leave yellow-orange
stains.  

I found that, when the Adchem phosphoric acid was applied over a surface
that wasn't treated previously with HCl that it could take it's time
drying after rinsing and it wouldn't rust, but it was a different
story if HCl was used first (even if the HCl was thouroughly rinsed off
and even if the Adchem stuff was applied twice).

I got pissed off at a couple of pieces and blasted them again and then just
wiped it down with my $15/pint rubbing alchohol (Quick Prep).

>water then dry.  I think this stuff may have been mentioned in a previous

Must be the Adchem stuff.
Muriatic Acid (HCl) is really cheap, and you can buy it by the gallon
at pool places (it's made for adjusting the ph of swimming pools).
It works really well at rust removal, but some people have mentioned
"Hydrogen embrittlement", but I don't know how long it takes for that
to happen, or how it affects subsequent paint jobs.

>Is it okay to use either or should I be using both?

Like I said, don't buy the quick prep unless they tell you why it's so
good, or if it's different than plain rubbing alchohol.

---

From: [email-masked] (Steven Malikoff)
Date: Tue, 7 Sep 1993 02:19:07 GMT

Wayne Smith ([email-masked]) said:
: I'm painting some car sheet-metal parts, with most of the paint taken
: off (ie down to bare metal).  I then brush on some muriatic acid and
: rinse with lots of water, then dry immediately.

Hang on, I'm pretty sure that Muriatic acid is nothing more than diluted
phosphoric acid(?). If this is the case, shouldn't you allow some time for
the rust to be converted to iron phosphate? (or whatever)

After rust removal, get some stuff called 'Prepsol'. It's very much like
thinners, but specially for cleaning surfaces for painting. I bought a 1 litre
tin for about Oz$12 and I've still got 1/3 tin left over after doing my jeep
body. You can get this stuff from automotive supplies places. After that,
I just apply a coat of red oxide. Then after final coats, I go around the
joins with some fishoil (this is *great* stuff).

Cheers,

Steve Malikoff.
[email-masked]

---

From: [email-masked] (bill nelson)
Date: Tue, 7 Sep 1993 05:46:27 GMT

[email-masked] (Steven Malikoff) writes:
: Wayne Smith ([email-masked]) said:
: : I'm painting some car sheet-metal parts, with most of the paint taken
: : off (ie down to bare metal).  I then brush on some muriatic acid and
: : rinse with lots of water, then dry immediately.
: 
: Hang on, I'm pretty sure that Muriatic acid is nothing more than diluted
: phosphoric acid(?). If this is the case, shouldn't you allow some time for
: the rust to be converted to iron phosphate? (or whatever)

No, it is hydrochloric acid.

Bill

---

From: [email-masked] (Chuck Lampman)
Date: Tue, 07 Sep 1993 08:14:47 -0500

> dust, etc) and then it flashes off without rusting the surface.

Right- that's exactly what it is. Also gets water molecules out of 
scratches, seams, etc., so you don't get bubbling later in the hot sun.

> or even rubbing alchohol (it can't be that bad).  

Rubbing alcohol is about half water and will rust the metal. Go to a paint 
store and get a gallon of pure denatured ethanol- like they use in stoves- 
it has no water in it.
 
> ......  I had problems with the rince though- unless I was very

Those yellow-orange stains are normal for phosphoric acid, don't 
worry about them. As long as the metal is dry after you use the 
acid and rinse it (the alcohol helps in this) you can prime. I like 
to do a final rinse down with a degreaser like Prep-sol or Ditz-O 
to get off fingerprints.
 
> some people have mentioned

It happens while the acid is on the steel- it causes the steel to crack 
because the surface is more brittle than the interior of the metal. I 
personally don't like HCl in bodywork- I think it causes more problems 
than it solves. I've done five restorations in the last ten years, and the 
only one where the paint has been a problem is the only one that I had
the body parts acid dipped with HCl. 
 
This whole area is one where a lot has been written, and a lot of 
research has been done by the paint companies.  The Petersen 
(Pederson? Peterson?) publishing company has several good books 
in the less than $10 range that cover the subject well.

Chuck Lampman
[email-masked]

---

From: [email-masked] (Chuck Lampman)
Date: Tue, 07 Sep 1993 10:57:03 -0500

Sorry all- that's twice this mailer has done that. I've fixed it...
Chuck Lampman
[email-masked]

---

From: [email-masked] (James W. Swonger)
Date: Tue, 7 Sep 1993 17:41:15 GMT

>store and get a gallon of pure denatured ethanol- like they use in stoves- 
 Some drug stores also have 70% and 95% isopropyl alcohol.

 If you're cleaning for lacquer, why not use lacquer thinner? It sure
takes grease off. Dries nice and clean, too. Problems with softening
Bondo/primer maybe? 

-- 
##########################################################################
#Irresponsible rantings of the author alone. Any resemblance to persons  #
#living or dead then yer bummin. May cause drowsiness. Alcohol may inten-#
#sify this effect. Pay no attention to the man behind the curtain. Billy!#

---

From: [email-masked] (Bruce Rowen)
Date: Tue, 7 Sep 1993 15:24:02 GMT

My advice is not to waste your money on this stuff.  Use an air gun,
   or even rubbing alchohol (it can't be that bad).  It the paint jobber
   ...........(stuff deleted)

                                   ^^^^^^^^^^^^^^^^^^^^^^^^

Rubbing alchohol contains glycerin (sp?), using this would be the same
as "cleaning" your metal with motor oil.

Use laquer thinner, acetone, toulene, or MEK instead.

--
-------------------------------------------------------------------------------
Bruce Rowen 				National Radio Astronomy Observatory
Scientific Programmer				Array Operations Center
[email-masked]			  P.O. Box O  Socorro, NM   87801
(505)385-7329					     (505)385-7000
-------------------------------------------------------------------------------

---

From: [email-masked] (Adam Karpowicz)
Date: Tue, 7 Sep 1993 23:37:02 GMT

>   good, or if it's different than plain rubbing alchohol.

As far as I know, the metal prep is alcohol with very small amount of
phosphoric acid in it - about 1 to 2 percent.  At such low concentrations
the residue is minimal and there is no need for rinsing afterwards. 
I used denatured alcohol with 2% phosphoric acid with good results, there
was no rusting, no yellow/orange stains etc.  
I suppose any solvent miscible with phosphoric acid (it comes as 80% solution
in water), such as isopropyl alcohol or acetone could be used.

Adam Karpowicz

---

From: [email-masked] (David Jenkins)
Date: 8 Sep 1993 09:56:03 GMT

Should we start an alt.paint.prep newsgroup?

;-)

-- 

David Jenkins

* All incorrect spelling and faulty grammar is intentional.   *  
* Corrections are superfluous and will be ignored.  So there. *         
*

---

From: [email-masked] (Bill Kish)
Date: Wed, 8 Sep 1993 14:34:49 GMT

About DuPont's Quick Prep alchohol base metal prep...

|> 

|> As far as I can tell, the stuff should really be called a surface cleaner
|> (ie drag a clean rag soaked with this stuff over the surface to remove
|> dust, etc) and then it flashes off without rusting the surface.
|> 
|> or even rubbing alchohol (it can't be that bad).  It the paint jobber
|> can't tell you why Dupont's Quick Prep is better, or different, than 
|> drug store alchohol, then he doesn't deserve $15 for a measely pint.

|> 
|> I sandblasted my stuff, but then I brushed on some HCl, and I noticed a
|> *big* difference in how the surface looked (the acid treatment looked
|> brighter).  The phosphoric acid treatment (Adchem) also made the surface
|> look brighter.  I had problems with the rince though- unless I was very
|> fast to dry the metal off after rinsing it would rust and leave
yellow-orange
|> stains.  
|> 

 This thread is turning very un(mis)informative! I've posted what I know 
 about Quick Prep earlier but I'll reiterate:

 1) HCl (muriatic acid) is not a subtable prep for ferrous metals. Don't 
    use it, you'll regret it.

 2) Quick prep is a very good product. It costs more, but it does the job
    better than most water-borne products and we are restorers here, right?

    I believe that Quick Prep is phosphoric acid in a isoprophyl base. 
    It has the advantage that it dries much faster than the water rinse stuff
    (unless you use Really Hot Water) which is extermely important for 
    sandblasted parts which are very prone to flash rusting due to the coarse
    surface. 

    Spray Quick Prep on to the parts with a spray bottle, avoid using a rag 
    since lint and contamination are a problem and more of the liquid is 
    wasted treating the rag instead of the parts. When the quick prep flashes
    off, you should see a nice blue-tinted surface with traces of white. This
    makes an excellent base for primer (but not bondo).

 Good luck, remember the manufacturers have hot-lines and local reps to 
 explain how to best use their products.

			-BK

---

From: [email-masked] (David Taylor)
Date: 10 Sep 1993 14:32:27 -0700

>Use laquer thinner, acetone, toulene, or MEK instead.
How about Ethyl alchohol You can buy it at drug stores and its supposed to
be medical level purity (alchohol+small amount of distilled water)

Or would this be corrosive? 

Also does anyone have experience with ospho is it a good rust-treetment for
automobile purposes??

Well
Hope this helps 
Thanks for any replys

Dave

---

From: [email-masked] (Ed Campbell)
Date: Fri, 03 Sep 1993 18:56:41 GMT

Ed Campbell

---

From: [email-masked] ()
Date: Sat, 4 Sep 1993 06:31:41 GMT

---

From: [email-masked] (Wayne Smith)
Date: Tue, 7 Sep 1993 01:15:48 GMT

---

From: [email-masked] (Steven Malikoff)
Date: Tue, 7 Sep 1993 02:19:07 GMT

Cheers,

Steve Malikoff.
[email-masked]

---

From: [email-masked] (bill nelson)
Date: Tue, 7 Sep 1993 05:46:27 GMT

Bill

---

From: [email-masked] (Chuck Lampman)
Date: Tue, 07 Sep 1993 08:14:47 -0500

Chuck Lampman

---

From: [email-masked] (Chuck Lampman)
Date: Tue, 07 Sep 1993 10:57:03 -0500

---

From: [email-masked] (James W. Swonger)
Date: Tue, 7 Sep 1993 17:41:15 GMT

---

From: [email-masked] (Bruce Rowen)
Date: Tue, 7 Sep 1993 15:24:02 GMT

^^^^^^^^^^^^^^^^^^^^^^^^

---

From: [email-masked] (Adam Karpowicz)
Date: Tue, 7 Sep 1993 23:37:02 GMT

Adam Karpowicz

---

From: [email-masked] (David Jenkins)
Date: 8 Sep 1993 09:56:03 GMT

;-)

-- 

David Jenkins

---

From: [email-masked] (Bill Kish)
Date: Wed, 8 Sep 1993 14:34:49 GMT

|> 

|> 

			-BK

---

From: [email-masked] (David Taylor)
Date: 10 Sep 1993 14:32:27 -0700

Well
Hope this helps 
Thanks for any replys

Dave

---

From: [email-masked] (Soren LaForce)
Date: Mon, 13 Sep 1993 17:02:00 GMT

In article <[email-masked]>, [email-masked] (David Taylor) writes...

>be medical level purity (alchohol+small amount of distilled water)

The only Ethyl Alcohol you can buy is denatured.  It will be contaminated
with something poisonous.  From an old memory of the entry in the CRC
handbook, the denaturing agent could be benzene, gasoline, kerosene,
etc.  Something to keep one from drinking the stuff, since there is 
no whiskey tax paid on it.  Some of the denaturing agents are probably
volatile enough to leave no residue but you would have to know what the 
alcohol has been denatured with.

If you not in california, you may be able to buy "everclear" at a 
liquor store.  However, the ~$11/gal tax will make it expensive.

Rubbing alcohol may work.  Isopropyl alcohol and water.  Poisonous
all by itself!

The orgianic solvents listed above all work well.  Don't breath
the vapors (use a chemical respirator), don't get them on your skin
(use gloves).

--Soren            [email-masked]

---

From: [email-masked] (Les Bartel)
Date: Wed, 15 Sep 1993 12:25:57 GMT

In article <[email-masked]>, [email-masked] (Soren LaForce) writes:
|> 
|> Rubbing alcohol may work.  Isopropyl alcohol and water.  Poisonous
|> all by itself!

It shouldn't be too hard to distill the alcohol out (catch and
condense the vapor).  Watch the temperature so you don't evaporate the
water too.

 - les

-- 
Les Bartel			I'm going to live forever
Intergraph Corporation		... or die trying
Electronics Division		
[email-masked]
or [email-masked] (preferred)
(205) 730-8537