|10-07-2005 08:10 PM|
|crashtech||I can't say I have the answer here, but I tend to follow some procedures that help ensure a job will have no visible problems from shrinkage. First of all, never feather filler up onto non-factory paint unless you KNOW it was all catalyzed and well cured. Second, never feather filler up over your paint featheredge unless it has been nicely feathered back with at least 150 grit, preferably 220. Third, make sure the featheredges are in 320 grit before priming. Fourth, let that primer flash off! Don't stand there and look at it, go do something else between coats, and set a timer if you tend to lose track of time. Fifth, don't apply thick coats. Just go one coat extra if needed. Now, I'm sure a guy could follow all these steps and still get shrinkage, but that would be rare, IMHO.|
|10-07-2005 01:29 PM|
If the product can safely be recoated in 5 minutes by the manufacturers own testing, then "Boasting" it can do that isn't an issue to me.
I think what you are thinking is that they would "push" the boast to sell product by saying it is faster than it really is. Now, that would be wrong.
Certainly, that happens from time to time. we all over sold ourselves on our first date.
But, really, really, the manufacturer with millions of dollars in products, with hundreds of millions of dollars on the line in warrantees isn't going to push that envelope. They want things to WORK, to NEVER be a problem, that is the goal.
|10-07-2005 01:24 PM|
An example is in my gun set up "Basics":
As an example of the use of a 1.3 tip I did a test once that proved the point well. I shot two panels of metal with a med solids urethane primer. One was shot with a 1.3 super high atomizing top of the line topcoat gun. The other was shot with a 1.5 (or a 1.7 I can’t remember) “hoser” primer gun. Three coats were applied and after a full cure (the one shot with the larger gun took MUCH longer to flash and cure by the way) the film thickness was measured. The one shot with the 1.3 tip was 2 tenths of a MIL thicker! The larger gun laid out the marble sized droplets full of solvent and when the solvent flashed the film shrank.
Now, the 1.3 tip may be too small for some products so check the tech sheet. The facts of the findings won't change.
|10-07-2005 12:55 PM|
That makes perfect sense to me.
Like Barry pointed out in another thread, that works good for buffing clear
too, after you sand it allow it to sit a few hours and it'll also buff better.
anytime you sand a surface you open it up to dry more.
|10-07-2005 12:36 PM|
Steering things back on course, if I may
I'd totally agree with the trapped solvents explanations, for any of the reasons given.
To illustrate, here's a little story:
We tend to prime all our repairs together, at the end of the day, to save wastage. When I was doing it, we hardly ever suffered shrinkage problems. Now the boss has begun to let our young lad do the priming, we are having regular problems (same product used).
He thinks that if he bombs 3 thick coats of 2k primer on the big repairs, with minimal flash times, he can go home early (and it'll 'hide' his poor filler work). The problem starts the day after. Upon hitting the primer with a DA, you can smell the solvents bursting out! I've even had it so bad, that the primer has popped right through the base and clear during baking!
Besides re-educating him, which is difficult as he is the boss's son, I've found one way around it is to block or DA the primer down early in the day, and leave it to sit as long as possible before final sanding. This seems to give the solvents time to escape, after 'breaking the surface', and shrinkage problems have been reduced.
Clearly, as stated above, the better way would be to take more time applying the primer, and allow plenty of flash time between coats, but maybe my method of 'breaking the surface' could help a little also.
|10-07-2005 11:49 AM|
|jcclark||Well obviously we have a different definition of boast.|
|10-07-2005 11:42 AM|
Well, I don't know where the boasting would be?
One example 1 hour buff.
No, actually 30 minutes at 75 degrees.
Always a safety net!
Or what about the 45 minute handling?
How about at 70 Degrees handle and put in rain in 30 minutes and will be water spot free.
Always a safety net!
So if you don't know why bring it up?
Because you don't have a clue.
Respond to someone else as I'm done here.
|10-07-2005 11:40 AM|
Well with that said.. i figured out the problem.. prolly putting on too many coats for this product to keep up.
The spi turbo 2k is great i have a gallon that ive been using on the porsche im restoring.. i plan on switching to that completly but i wanna use up the rest of this nason.. ill just stick to 2 or 3 coats and i wont bomb them on as sometimes happens. thanks guys
|10-07-2005 11:21 AM|
Read this advertisement, if this is not boasting I stand corrected.
Thank you for viewing our website. Please click on any of our products and view their respective tech sheets. By doing so you will find that our 2K primers are ready to sand in 30 minutes at 70 degrees and do not require a sealer.
You will see that our clears can be buffed in as little as 1 hour, handled in 45 minutes, and buff good as much as 30 days after application. Our epoxy primers spray wet and slick, and all of our colors, including white, have outstanding adhesion to aluminum.
Our spray-in truck bed liner is tintable with such strength that we make counter mats out of them for our jobber stores! Let us prove to you that we believe in quality over quantity, and that we stand behind all of our products.
|10-07-2005 11:15 AM|
No, but I'll tell you this, if they would have been in a more competitive area like Contra Costa County just west of the SF bay area they would have! I am not kidding, in that area DuPont and PPG thru so much money at shops it was sickening. A little shop like this with only $3000 or so in monthly purchases would be fought over and given $20,000 or something. It was sick.
Up where this Ford dealer was at in Lake county, DuPont and PPG didn't even send a rep up there. I got a lot of business up because I was willing to go. Those shops didn't even know about the incentive checks the big boys were tossing around.
|10-07-2005 11:05 AM|
You are right! But I bet you did not see Dupont or PPG or yourself go into those places and try to buy the business with two free paint booths and a million dollar check up front for a 3 year contract to get their business either.
|10-07-2005 11:01 AM|
However Barry, there are "Chevy dealers" with some pretty funky set ups.
I serviced a Ford dealer in a small town with a home made booth!
|10-07-2005 10:38 AM|
No, No and No.
A company is not going to boast their products!
The risk of this is to great, as a matter of fact its usually the other way around.
When was the last time you saw a dealership build a fender out of filler and spray 6 coats of 2K on it to start? Most of their work is two coats of primer as they are panel re-placers.
If a major writes a tech sheet for primer, its written for a Chevy dealer that has good painting conditions and the shop will not be under 70 degrees in the winter time and is going to be as close to lab conditions as your going to get.
They don't write tech sheets for spraying at home as number one we have Chevy and Ford dealers around here that spend $60,000 and up a month on paint materials, so that is their big business.
Its up to you to adjust for colder or hotter weather and size of car your doing. This is not furniture painting.
|10-07-2005 09:21 AM|
These are some good points and shows that every rule has exceptions.
To say always follow the mfg recommendations has exceptions here too.
Waiting longer is better, true they give min times usually but they like
to boast their product with fast time advertisements to lure bodyshops
into buying their pruduct. There's a lot of things you can get away with
in the "perfect world environment" as they give directions to but for most
people like me that screw things up all the time it's better to error on the
side of safety. That's why I advise letting primer set 3 days before sanding
and clear to set more than 24 hrs. There's not always time to do that
and all products are different,but waiting longer helps.
|10-07-2005 08:52 AM|
|baddbob||Another thing that can cause shrinkage problems is epoxy primer if applied too heavy without enough cure time especially if more than one coat is applied. Epoxy is a slow drying primer. If you do your work and apply epoxy then your urethane surfacer while the epoxy is too wet the faster curing urethane primer will seal and slow the cure rate of your epoxy. Just another example of bombing products on and the problems that can happen. And a reason why most collision shops won't use epoxy even though the durability is so much better than any etch or DTM urethane. IMO any restoration or show car quality jobs should be allowed more cure time than regular production/collision work-how long depends on what products are used, temperatures, application.... Give longer flash times between coats, make sure you keep the shop warm, don't apply more coats than suggested and the right thickness. A heat lamp is also a good investment if you need to speed things up-just be sure to give the primer time to purge the solvents before you apply the heat. I have absolutely no shrinkage problems.|
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