Today's Message Index:
----------------------
1. 06:56 PM - Paint Questions (Steven Jackson)
2. 09:26 PM - Re: Paint Questions (Gil Alexander)
3. 09:59 PM - Re: Paint Questions (TeamGrumman@AOL.COM)
4. 10:37 PM - Re: Paint Questions (Steven Jackson)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> TeamGrumman-List message posted by: "Steven Jackson" <steven.jackson14@adelphia.net>
TG,
As an example of Bob Steward's closing comments of his GG post today, I have
some questions.
Yesterday, primer went on my first of two stabs quite well. Today, the
topcoat was disastrous...
CONDITIONS:
-In my garage, no wind, humidity around 20%, air temperature in the low
70's.
SETUP:
-Sata gun requiring 29 psi at the gun and 3.8 cfm (minijet)
-Air compressor set at 50 psi at the regulator with a flow at that setting
of ~6 cfm.
-Sata micrometer at the gun set for 29 psi.
-Filter on hose just before the gun, and 3/8 hose, 50 feet of hose.
PAINT:
-PPG Imron equivalent (acrylic polyurethane, can't remember the name off
hand) mixed properly with hardner, thinned with recommended thinner. Didn't
get IMRON because the local store only sold PPG stuff.
-Had trouble figuring quantity of thinner, as it says up to 10% and I was
only mixing about 6 oz of paint (possibly added too much thinner).
RESULTS:
-Both bottom and top of stab had lots of tiny little air bubbles after the
tack coat. Checked my troubleshooting manual and couldn't really find an
answer for that one. Noticed that while the pressure on the gun in a
sustained spray was 29 psi on the micrometer, it starts out higher--say 40
psi for about 1/2 second, then drops to 29.I figured that the higher
pressure would be gone by the time I was over the stab, since I start my
stroke off the stab, then work across. But, thought possibly that the
combination of possible high pressure and possible excess thinning may be
the cause. Also, I assume the second step is to sand the paint to remove
the bubbles and then repaint. How long should I wait to sand--a day, two?
Any thoughts???
Steven Jackson
N1434R
L22
Yucca Valley, CA
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Paint Questions |
--> TeamGrumman-List message posted by: Gil Alexander <gilalex@earthlink.net>
Steve ... sounds like solvent popping to me...
http://www.autobodydepot.net/sol/sol26.html
perhaps you need a different thinner for the 20% local humidity... or your
paint coats were too heavy.
For mixing small amounts I've found that a digital scale that reads in
grams to be pretty effective.
good luck gil in Tucson
At 06:55 PM 9/28/2004, you wrote:
>--> TeamGrumman-List message posted by: "Steven Jackson"
><steven.jackson14@adelphia.net>
>
>TG,
>
>As an example of Bob Steward's closing comments of his GG post today, I have
>some questions.
>
>Yesterday, primer went on my first of two stabs quite well. Today, the
>topcoat was disastrous...
>
>CONDITIONS:
>
>-In my garage, no wind, humidity around 20%, air temperature in the low
>70's.
>
>SETUP:
>
>-Sata gun requiring 29 psi at the gun and 3.8 cfm (minijet)
>
>-Air compressor set at 50 psi at the regulator with a flow at that setting
>of ~6 cfm.
>
>-Sata micrometer at the gun set for 29 psi.
>
>-Filter on hose just before the gun, and 3/8 hose, 50 feet of hose.
>
>PAINT:
>
>-PPG Imron equivalent (acrylic polyurethane, can't remember the name off
>hand) mixed properly with hardner, thinned with recommended thinner. Didn't
>get IMRON because the local store only sold PPG stuff.
>
>-Had trouble figuring quantity of thinner, as it says up to 10% and I was
>only mixing about 6 oz of paint (possibly added too much thinner).
>
>RESULTS:
>
>-Both bottom and top of stab had lots of tiny little air bubbles after the
>tack coat. Checked my troubleshooting manual and couldn't really find an
>answer for that one. Noticed that while the pressure on the gun in a
>sustained spray was 29 psi on the micrometer, it starts out higher--say 40
>psi for about 1/2 second, then drops to 29.I figured that the higher
>pressure would be gone by the time I was over the stab, since I start my
>stroke off the stab, then work across. But, thought possibly that the
>combination of possible high pressure and possible excess thinning may be
>the cause. Also, I assume the second step is to sand the paint to remove
>the bubbles and then repaint. How long should I wait to sand--a day, two?
>
>Any thoughts???
>
>Steven Jackson
>N1434R
>L22
>Yucca Valley, CA
>
>
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Paint Questions |
--> TeamGrumman-List message posted by: TeamGrumman@aol.com
In a message dated 9/28/04 6:59:04 PM, steven.jackson14@adelphia.net writes:
> -Both bottom and top of stab had lots of tiny little air bubbles after the
> tack coat.=A0 Checked my troubleshooting manual and couldn't really find an
> answer for that one.=A0 Noticed that while the pressure on the gun in a
> sustained spray was 29 psi on the micrometer, it starts out higher--say 40
> psi for about 1/2 second, then drops to 29.I figured that the higher
> pressure would be gone by the time I was over the stab, since I start my
> stroke off the stab, then work across.=A0 But, thought possibly that the
> combination of possible high pressure and possible excess thinning may be
> the cause.=A0 Also, I assume the second step is to sand the paint to remove
> the bubbles and then repaint.=A0 How long should I wait to sand--a day, two?
>
First of all, you have the wrong kind of pressure regulator. Get a decent
one. They cost about $35.
Second, you really need the Sata jet that shoots in the 11-15 cfm for decent
paint application.
Third, the air bubbles. It's called solvent popping. It's a mismatch
between the reducer you're using, the volume of paint applied, the application
pressure (I always use a mucch higher pressure than recommended; in the 30-35 psi
range.) and the ambient temp. You said it was 70s but what was the temp of
the part? I had a problem about a year ago with Imron and solvent popping.
I'd never seen it before. The new paints really suck and you need to find
what combination works for you.
Fourth: Never start painting a new part without painting test pieces first.
I painted a part about a year ago that I had to paint 5 times. I ended up
painting it at 3 in the morning when it was cooler.
Gary
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> TeamGrumman-List message posted by: "Steven Jackson" <steven.jackson14@adelphia.net>
Well, I assume the part was basically close to air temperature--it had sat
in the garage all day. When you say pressure regulator, would that be
something on the gun or at the compressor? Like I said, I've got the Sata
micrometer that's supposed to regulate the pressure at the gun. I'll mix a
small batch of paint tomorrow with higher pressure--I was just following the
instructions with the gun. I'll probably go with a small batch that's not
reduced and another one that is and try both. The solvent popping wasn't
severe (large bubbles) so I'm hoping they'll sand out.
Thanks for the help...
Steve
-----Original Message-----
From: owner-teamgrumman-list-server@matronics.com
[mailto:owner-teamgrumman-list-server@matronics.com]On Behalf Of
TeamGrumman@AOL.COM
Subject: Re: TeamGrumman-List: Paint Questions
--> TeamGrumman-List message posted by: TeamGrumman@aol.com
In a message dated 9/28/04 6:59:04 PM, steven.jackson14@adelphia.net writes:
> -Both bottom and top of stab had lots of tiny little air bubbles after the
> tack coat.=A0 Checked my troubleshooting manual and couldn't really find
an
> answer for that one.=A0 Noticed that while the pressure on the gun in a
> sustained spray was 29 psi on the micrometer, it starts out higher--say 40
> psi for about 1/2 second, then drops to 29.I figured that the higher
> pressure would be gone by the time I was over the stab, since I start my
> stroke off the stab, then work across.=A0 But, thought possibly that the
> combination of possible high pressure and possible excess thinning may be
> the cause.=A0 Also, I assume the second step is to sand the paint to
remove
> the bubbles and then repaint.=A0 How long should I wait to sand--a day,
two?
>
First of all, you have the wrong kind of pressure regulator. Get a decent
one. They cost about $35.
Second, you really need the Sata jet that shoots in the 11-15 cfm for decent
paint application.
Third, the air bubbles. It's called solvent popping. It's a mismatch
between the reducer you're using, the volume of paint applied, the
application
pressure (I always use a mucch higher pressure than recommended; in the
30-35 psi
range.) and the ambient temp. You said it was 70s but what was the temp of
the part? I had a problem about a year ago with Imron and solvent popping.
I'd never seen it before. The new paints really suck and you need to find
what combination works for you.
Fourth: Never start painting a new part without painting test pieces
first.
I painted a part about a year ago that I had to paint 5 times. I ended up
painting it at 3 in the morning when it was cooler.
Gary
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|