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  #16 (permalink)  
Old 12-18-2004, 10:57 AM
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Good Lord, I've created a monster. I don't think anyone out there
is reading what the other is saying.
I only read one response that comes close to my question.
First of all, yes a overall paint job is "one" paint job. that is not
the same as the second coat becoming "one" with the first.
Lacquer does this, it melts the previous coat and if you looked
at several coats under a microscope they would look like
"one" coat. period! base coat and clear coat stay separate,
they may be stuck together but they're still separate.
Thay can be parted. And sometimes they do.
Second: When I asked about flash time I'm not asking when
I "can" recoat. I know that, it's right on the can 30Min to 24 hrs.
What I'm asking is when is the best time. The best time won't be
feasable for the production shop, that's not me.
If waiting 2 hrs is better than 30min I will do that.
To me, the more dry the base the better I would think.
within reason of course. It may be dry enough at 30 min but
remember, that's the minimum! I don't want the minimum
or the maximum. Maybe the middle is best? 12 hours.
I know this is a moot point that none of us will do but
think about it. 30 min dry may never give you a problem
but does that really mean that it's the "best"?

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Old 12-18-2004, 11:08 AM
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Quote:
Originally posted by MARTINSR
Come on now guys, let's not have a peeing match. This is very , very good stuff, let's not cloud it up.

When I say that trapped solvent is the number one cause of failure I am not kidding. Trapped solvent in one way or another does more damage than any other mistake, PERIOD.

Because of this, it is very important to talk about.

Troy, I think the most important word is "optimum". It is optimum to wait out that flash recommendation. Not that everyone does it, certainly not in collision shops. There are lots of things that go on in collision shops that is far from optimum.

The one thing a shop has in it's favor that a home hobbyest does not have is the booth. You can push a lot more when you have booth with the air movement it provides to "pull" the solvents out of the film.

With a car sitting in a garage with a little box fan in the window to suck out the overspray, you have a completely different condition. These flash times, solvent temp choice, gun speed, gun setup, air supply (read that CFM) etc. become much more of an issue.

Honestly Troy, clear coat peels are caused by applying the clear too soon far more than waiting too long. I saw plenty of clearcoat peels from collision shops, the S-W recoat max is seven days, the collision shop certainly didn't wait too long that is for sure. They pushed it, to get the cars out the door and trapped solvents under the clear. The next time you see a "peeler", try this. Peel some of the clear off and stick your nose down to the base that has been exposed, you will many time smell solvents! You will smell the solvents that were trapped under the clear!


Barry, on that note, I always wondered about that seven day window thing, how in the heck can they have it that long when similar products are so much less at 24 hours? I can not imagine waiting 7 days to clear something, I have waited till the next day a number of times, but there is no way I would wait 7 days, that just gives me the willys thinking about it.
***********************************************

Very well said!
bwk
Not sure what you mean about seven day window?
I I only know of one base with no window and don't think its made any more.
Thanks
Barry
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  #18 (permalink)  
Old 12-18-2004, 11:19 AM
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Barry, yeah, S-W had a seven day max recoat time on the UltraBase. Go to the bottom of the second page HERE .
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Old 12-18-2004, 11:59 AM
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Not really a problem,
because of its enamel makings!
It could really go longer as long as not activated maybe
even 60-90 days-(just guessing) the biggest concern
would be how long you can go before this base sensitizes itself. You want the clear applied before that happens to prevent lifting. Every system has its positives and negatives, and this is a positive no doubt.

You can bet, if SW says 7 days the sensitivity does not kick in for 14 days or so.

Last edited by BarryK; 12-18-2004 at 12:09 PM.
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Old 12-18-2004, 01:09 PM
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Martin, I've painted lots of cars with only a box fan for ventilation, the only problems I had was trash, bugs, etc. The only times I ever needed a paint rep was for color match problems.

I agree with most of what you say, except the statement about more problems with peeling because of cc being applied to soon and I agree with that, if there was not enough flash time, if you wait for the recommended flash time, there should be no problem. As I never kept a chart of the times I've waited for flash, and I've never had any problems except when waiting to long. So in my opinion the sooner you cc after you get a flash and the air has cleared, the less likely that there will be any problems with adhesion.

As far as sniffing the bc after the cc has peeled, it would be hard to tell the difference between thinner and paint.

I have learned over the many years in the business that not many shops or painters do it the same, this procedure has worked for me quit well.

Troy

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  #21 (permalink)  
Old 12-18-2004, 01:37 PM
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Quote:
Originally posted by jcclark
Good Lord, I've created a monster. I don't think anyone out there
is reading what the other is saying.
I only read one response that comes close to my question.
First of all, yes a overall paint job is "one" paint job. that is not
the same as the second coat becoming "one" with the first.
Lacquer does this, it melts the previous coat and if you looked
at several coats under a microscope they would look like
"one" coat. period! base coat and clear coat stay separate,
they may be stuck together but they're still separate.
Thay can be parted. And sometimes they do.
Second: When I asked about flash time I'm not asking when
I "can" recoat. I know that, it's right on the can 30Min to 24 hrs.
What I'm asking is when is the best time. The best time won't be
feasable for the production shop, that's not me.
If waiting 2 hrs is better than 30min I will do that.
To me, the more dry the base the better I would think.
within reason of course. It may be dry enough at 30 min but
remember, that's the minimum! I don't want the minimum
or the maximum. Maybe the middle is best? 12 hours.
I know this is a moot point that none of us will do but
think about it. 30 min dry may never give you a problem
but does that really mean that it's the "best"?
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Sorry for the confusion,
but you said you read one post and now you have other questions. nasty or not this has covered some very good and important ground. (there will always be different opinions some fact and some hearsay)
Everyone of your questions has been answered!
So read all the posts and pay attention about the graph as that is how companies decide how to set the wide rage of open-coat, and use common sense with the graft and all your questions will be answered.
Barry
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  #22 (permalink)  
Old 12-19-2004, 09:30 AM
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I've cleared S-W base that has sat for more than 7 days with no problems BUT it was on helmets that had multiple colors and they are still fine today , a car with all the everyday conditions would probably be different.

jcclark , If I were you ,being that you are doing this in less than optimum conditions , I would base it the one day , than go ahead and clear the next . If you have any doubts whatsoever , maybe go over the car quickly the next day with a grey scuff pad to just scuff it a bit .
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Last edited by outlaw17; 12-19-2004 at 09:36 AM.
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  #23 (permalink)  
Old 12-19-2004, 12:11 PM
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You really shouldn't scuff the base. You "can" do it, but it opens up a huge window for problems. Some bases are very sensitive and marking or scratching will uccur that the clear won't hide.

If you do scuff it is usually a good idea to apply another coat of color.
Like I said, you can scuff some bases, but some you can not.
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  #24 (permalink)  
Old 12-19-2004, 01:07 PM
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MARTINSR I would assume has a bit more experience than me so ya better listen to him . I have had no problems doing it the little bit that I have but I also have never had anyone tell me not to do it up until his above post . You learn something every day here at the Hotrodders forum
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  #25 (permalink)  
Old 12-20-2004, 10:31 AM
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I've always had to spray more base if I scuff. It always changed
the appearance when I scuffed. Just this past Sat. I sprayed
2 fiberglass fenders with black base and it revealed a lot
of scratches in the primer. I scuffed with a gray pad
untill they were gone, sprayed a couple new base coats
and it looked perfect. I waited an hour to clear and then
long enough between coats that it was well flashed.
The temp was less than 50 deg. (I used the coldest thinner)
It took me a total of 6 hrs. But waiting longer between coats really gave me a better finish. I had less dye back, a smoother finish and it didn't tend to run.
It was my best ever. After they "set-up" I
brought them inside to warm and cure. They look great.
I'm going to start waiting longer between coats.
I have been just to impatient in the past.
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Old 12-20-2004, 01:29 PM
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OK now I have a question, If you spray(BC?CC) at less than 50 deg. how long can you go before bringing the temperature up high enough to properly cure? Also would a brief exposure after spraying of about 10-15 minutes to even colder temperature cause any problems? Cold temps are problem for me right now.
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  #27 (permalink)  
Old 12-20-2004, 05:18 PM
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Base is a different issue.
If at all possible pre warm the metal to 65-75 than shut off heat and spray.
Word of caution is, if metal is cold and you apply your coats than turn on heat solvents will trap in coat closest to metal.
Thats why preheating is most important.
When you apply heat after done, is really not an issue but make sure you give it longer than normal before clearing. This would be a good case for letting base set over night before clearing.

Also this would be a time Not to use an activated base for best results.
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