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  #1  
Old 06-16-2011, 01:44 PM
Stretch's Avatar
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Cleaning paint work whilst painting!

G'day Folks,

I've been busy painting my car for some time - see

I've taken your advice and started to paint!

On some bits of the car I'm getting quite close to being happy enough to start spraying the clear varnish top coat.

Now - in an ideal perfect world, according to Standox, I should be applying the coats of paint within 8 hours of each application - however a quick look at the date of the first post of this thread and the date of this post shows that I've missed that window of opportunity.

So before I apply a top coat I want to clean what I've got.

Has anyone used stuff like this before?

http://www.amazon.com/U-POL-Solvent-.../dp/B004SQM1DQ

U Pol slow degreaser.




I've tried Eastwood panel prep but that stuff behaves more like paint stripper on Standox base paint. It is really meant for bare metal...

http://www.eastwood.com/pre-painting-prep-gallon.html



Or should I use a mild household soap and plenty of clean water?

I've got some of those handy little microfibre wipes that are meant to pick up dust and muck - should I just stick with those?

As usual thanks for any help you can provide.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #2  
Old 06-16-2011, 04:04 PM
compress ignite's Avatar
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On the Upol

This is the only Caveat I would insist on:
"Carefully formulated to avoid any attack on existing paint films."
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  #3  
Old 06-17-2011, 08:06 AM
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The problem is you are not just laying down another coat of paint. You want the clear to "bond" with the underlaying layer. Once the paint has cured it is no longer a porous surface for the new layer of clear. You are going to have de-lamination problems out the kazoo.

You are going to need to re-spray and THEN apply the clear.

Double check with JMK but I'm afraid this is what he is going to tell you.
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  #4  
Old 06-17-2011, 10:49 AM
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OK thanks folks - it is good to know at this stage in the game - and not later.
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #5  
Old 06-21-2011, 05:40 AM
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I asked Standox customer support and here is their reply.

Very helpful I think

<QUOTE>

There are lots of factors that will determine whether the paint film will delaminate, your conditions will play a factor, as if the vehicle is "sat" in basecoat condition for a number of days there is a possibility moisture could be absorbed the surface layer, it is very difficult to give you exact advise without knowing allot more detail.

If the vehicle has been in basecoat for a while then I would recommend the follow process below:

1) Warm the vehicle to approximately 30 degrees centigrade if possible for 30 mins this will hopefully drive off any moisture that may be present in the surface,

2) If necessary lightly sand any areas with dirt etc using P1200 - P1500 dry

3) Once complete, use a tack cloth to wipe the vehicle to remove any fine dust particles etc.

4) Apply one last coat of basecoat and then if necessary over thin the basecoat and apply a "control coat" to eliminate any mottle within the paint film, (All paint application this should be carried out at approximately twenty degrees C).

5) Allow to dry for approximately one hour at an ambient temperature (approx 20 degrees C)

6) Tack cloth off the entire vehicle again

7) Mix clearcoat and apply as per Standox Technical Data Sheets (A two component clear contains Isocyanate in the hardener and is harmful to your health, we only recommend a air feed respirator should be used when applying a 2K clearcoat).

<END QUOTE>

Now I know what to do.
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #6  
Old 06-21-2011, 07:12 PM
jmk jmk is offline
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Reasonable advice, and it is sometimes hard w/o actually seeing the car.

I was just giving some advice to a person at work who has a Olds 442 where he was having problems with the paint.

You do get into adhesion issues if you wait too long to place the clear on.

1) adhesion because the basecoat has crosslinked too much to promote adhesion.

2) water contamination: isocyanate will readily self condense in the presence of water and cause all type of adhesion and appearance issues. That is why you pay so much for "urethane grade" solvents. The big reason they cost more is that all of the water has been removed from them.

There are some advantages in waiting

1) excess solvent from the basecoat has the chance to evaporate. This is especially true if the the basecoat was applied too thick, or the cure was retarded from excessive cold weather.

2) appearance will be better. The DOI (distinctness of image) or clarity of the coating will be better if the clearcoat and basecoat do not intermix. One of the tricks that I employed when developing OEM coatings was to carefully match the cure rate of the basecoat with the clear to maximize appearance.

The guy who sprayed his Olds had too thick of a basecoat. He ended up having solvent bleed from the basecoat bugger up the clearcoat. It happened a couple of weeks after he painted it. The solvent worked its way through the film and wrecked the finish in certian areas.

Now, what to do. Without actually seeing what you have, it's hard to say. If you remember earlier, I mention not to use too much basecoat. Spray it until you get consistent hide, no more. Now, I have seen shops wait as much as a week before applying the clear. They did not have any delamination issues, but that workability window can have a lot of variables in it.

Personally, I do not think that the base has cured too much after a week of air drying for the clear to adhere to the basecoat. The water contamination is the real issue. The shops that waited to clear had 50-60 C bake ovens to force the cure to completion once the clear was applied. I do think delamination due to water contamination would be more of an issue than basecoat cure. I do like the idea of raising the body temperature to drive off water. That would be prudent.

I wouldn't use any of those spray strippers since they may have solvents that could be inbedded in the basecoat and give you issues like the Olds example. Since I've never used them myself, I like to be corrected on this point if someone has.

There is significant post cure in refinish coatings for the first 30 days after application. I do not think adhesion due to basecoat cure is the issue here. Contamination is the biggest issue, esp. water contamination. BTW, it sounds like the basecoat you used was single component. If that is true, then you would have a lot more time for the coatings to chemically adhere to each other. Also, since the basecoat wouldn't be crosslinked (where two or more components of the paint chemically change when drying), you wouldn't have the basecoat becoming chemically more difficult to bind to. Again, if the basecoat is single component, then there is more possibility for cure issues.
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  #7  
Old 06-22-2011, 01:40 AM
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Right jmk - thanks for all of that - fantastic advice.

I am using a single component base coat. It is called Standox base.

So in my situation water is the enemy particularly as most of the car is being painted outside (in Northern Europe).

From the practical limitations that I've got I guess it all comes down to a balance between dirt and water ingress problems verses adhesion to a base coat problem...


...Oh for a hydroscopic cleaner that won't strip my base coat!
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #8  
Old 06-22-2011, 04:24 PM
jmk jmk is offline
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If you're outside in Holland, water is a major concern. I'm sure Holland is about as dry as Hamburg (I lived there 20 years ago).

Since you've confirmed that the basecoat is single component, then spray away. Waiting will not help your situation, and you do not really have to worry about the basecoat being overy crosslinked.

I would get rid of dirt with a tack cloth.

Water and dirt are your enemy.

The respray of the basecoat that the tech center suggested. I really do not understand why they are suggesting that. I can only guess that the extra coat may displace any water. I cannot see how a single component material could crosslink enough in such a short of time to prevent a 2k urethane clear from biting into it.

The suggestion on overthinning some basecoat and spraying to reduce mottle is just for apparance, not adhesion. Faster evaporating and more solvents help mottle. The disadvantage of more solvent is higher VOC's, the disadvantage of faster evaporating solvents is a rougher basecoat.

Hope this helps, but this is really hard to analyze w/o being there.
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2010 Toyota matrix

'93 500 SEL
A bad addiction. Takes all of my cash.

'12 Volvo S80 T6
Needed something that wasn't as hard to deal with as my bad addiction

'18 Mazda Miata
No more boring cars for everyday transport!
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  #9  
Old 06-25-2011, 03:00 PM
Stretch's Avatar
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Join Date: Sep 2009
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Quote:
Originally Posted by jmk View Post
...

Hope this helps, but this is really hard to analyze w/o being there.
I'm quite sure it is. Thanks for your help anyway - Although I'm kind of in a unique position where I can mess about and try different stuff I think it is about time I got my act together and got that bloody top coat on. At least if it gets messed up now I've got enough experience to get it back to the stage where I'm at now a whole lot more quickly.
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #10  
Old 08-02-2011, 11:13 AM
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Update I bought some of that U-pol slow degreaser - so far it seems like good stuff.

For months now (feels like years) I've been taking off the tarpaulin off of the car on dry days and putting it back on before the next down pour. This seems to be the way to make sure the car stays as dry as possible. Never leave a car under a tarpaulin and expect it to be dry when you remove it months later...

Anyway the surface of the car has collected quite a lot of dust and muck during this period of waiting for good weather and I didn't fancy using water to clean it all off - or even a damp rag - so I bought this U-Pol slow degreaser to remove any muck and gunk before I sand.

So far I can report that this stuff does not seem to attack primer, spray filler, or Standox base.

You really need a respirator though.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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