9 replies to this topic

[Brad Will]

Hi Dr. G- I know you did work for PPG in the past. I am curious as to what your opinion is on waxing/sealing fresh paint and why. Thanks for your reply.

[Doctor G]

Brad Will, on Feb 5 2008, 08:56 AM, said:

Hi Dr. G- I know you did work for PPG in the past. I am curious as to what your opinion is on waxing/sealing fresh paint and why. Thanks for your reply.

Brad,

Thank you for bringing up this question. There is a great deal of confusion regarding polishing or waxing fresh paint. The majority of refinish paint supplied by PPG, Dupont, Sherwin Williams, and BASF (which covers over 90% of the market) is two component polyurethane paint. One component is polyisocyanate and the second component is polyol (acrylic polyol or polyester polyol). Whether these are waterborne (due to EPA requirements) or solvent borne (majority of what is still being used) once the two components react and form a polymer it is not affected by most solvents (with the exception of paint removers such as methylene chloride).

As far as polishing goes, factory paint is baked and cured rapidly and is polished as it comes out of the paint booth. Refinish paint is generally not baked and is polished within a day of being painted. So polishing paint that is at least a day old is perfectly fine.

While refinish paint is about 90% cured within 24 hours, it does take up to 30 days for it to fully crosslink and cure. During this period, using solvent based waxes and sealants is not ideal since the solvents penetrate the paint and soften it and if the wax or sealant contains abrasives (the white powdery residue that is wiped off), it can cause micro marring on the softened paint. The best products to use during this period are therefore water based systems that are abrasive-free.

To sum these up, on paint that is less than one month old, you can use water based waxes or sealants that have no petroleum solvents or abrasives (leave no powdery residue). I hope that answers your question.

David,

[Brent]

Doctor G, on Feb 5 2008, 11:07 PM, said:

Brad,

Thank you for bringing up this question. There is a great deal of confusion regarding polishing or waxing fresh paint. The majority of refinish paint supplied by PPG, Dupont, Sherwin Williams, and BASF (which covers over 90% of the market) is two component polyurethane paint. One component is polyisocyanate and the second component is polyol (acrylic polyol or polyester polyol). Whether these are waterborne (due to EPA requirements) or solvent borne (majority of what is still being used) once the two components react and form a polymer it is not affected by most solvents (with the exception of paint removers such as methylene chloride).

As far as polishing goes, factory paint is baked and cured rapidly and is polished as it comes out of the paint booth. Refinish paint is generally not baked and is polished within a day of being painted. So polishing paint that is at least a day old is perfectly fine.

While refinish paint is about 90% cured within 24 hours, it does take up to 30 days for it to fully crosslink and cure. During this period using solvent based waxes and sealants is not ideal since the solvents penetrate the paint and soften it and if the wax or sealant contains abrasives (the white powdery residue that is wiped off) can cause micro marring on the softened paint. The best products to use during this period are therefore water based systems.

To sum these up, on paint that is less than one month old, you can use water based waxes or sealants that have no petroleum solvents or abrasives (leave no powdery residue). I hope that answers your question.

David,

Thanks for the reply Dr. G. Opti-Seal and Poli-Seal are both solvent based while Optimum Car Wax is water based correct?

[Doctor G]

Brent, on Feb 6 2008, 08:14 AM, said:

Thanks for the reply Dr. G. Opti-Seal and Poli-Seal are both solvent based while Optimum Car Wax is water based correct?

Brent,

That is correct. Of course all the discussions here apply to refinish paint that is less than a month old.

David,

[Doctor G]

Brad Will, on Feb 6 2008, 08:15 PM, said:

Thanks Dr. G. That clarifies a lot questions I, and others have had regarding this subject.

Brad,

I am sure this clarification will create more questions than answers, however, please feel free to share my post in its entirety with anyone you like. Thanks.

David,

[Anthony Orosco]

The problem people have with this is...."Who to believe?" Right Brad?

Well when Dr. G. says there should be no products with abrasives used on a curing paint is so that excessive marring will not be introduced into the soft paint. When a body shop wet sands and buffs out a painted panel they are doing so by abrasive means and they are hopefully polishing all the scratches and swirls out (although this is usually not the case).

Now when the consumer goes home and they wax the paint with an abrasive all in one type product and introduce marring they can then be screwed as they may then think they need something more abrasive to fix it....and we have a big mess starting.

Also, most body shops do not "oven bake" their refinish work because this would then play foul with the rubber materials. They either place the panels in the sun or they use heat lamps but this is not the same as "baking".

Solvent based products, as noted by Dr. G., may also play foul with curing paints because, as I understand it, they may keep the paints from fully curing or at least may cause problems within the cured/curing paint.

The better question to ask is this: Could it be that body shops recommend 30 days or longer because some paint suppliers place a 30 day or so warranty on their paints?

Hope that helps,
Anthony

[Doctor G]

Anthony Orosco, on Feb 6 2008, 11:23 PM, said:

The problem people have with this is...."Who to believe?" Right Brad?

Well when Dr. G. says there should be no products with abrasives used on a curing paint is so that excessive marring will not be introduced into the soft paint. When a body shop wet sands and buffs out a painted panel they are doing so by abrasive means and they are hopefully polishing all the scratches and swirls out (although this is usually not the case).

Now when the consumer goes home and they wax the paint with an abrasive all in one type product and introduce marring they can then be screwed as they may then think they need something more abrasive to fix it....and we have a big mess starting.

Also, most body shops do not "oven bake" their refinish work because this would then play foul with the rubber materials. They either place the panels in the sun or they use heat lamps but this is not the same as "baking".
olvent based products, as noted by Dr. G., may also play foul with curing paints because, as I understand it, they may keep the paints from fully curing or at least may cause problems within the cured/curing paint.

The better question to ask is this: Could it be that body shops recommend 30 days or longer because some paint suppliers place a 30 day or so warranty on their paints?

Hope that helps,
Anthony

Anthony,

Thank you for making these clarifications. As you pointed out, there is a huge difference (a couple of hundred degrees) between factory baking the entire painted body vs. bodyshops heating the painted panels.

There is one other factor that needs to be pointed out regarding refinish paint. Bodyshops use 10-20% more isocyanate component (hardener) than the polyol component. The reaction between these two (isocyanate and alcohol) is fairly rapid and that accounts for the 90% curing rate of the refinish paint within 24 hours.

However, there is about 10-20% unreacted isocyanate left in the paint. Some of these isocyanate groups slowly react with moisture (hence the term moisture cure) and form amine groups (releasing CO2). The newly formed amine groups rapidly react with isocyanate groups to form urea (or polyurea as a whole). Polyurea is much harder than polyurethane.

As I mentioned, this reaction takes more time and requires moisture for completion. Adding solvents to the paint hinders this reaction while water-based products can help the curing process.

David,

[Brad Will]

Anthony- There was a topic started on Autopia recently regarding this subject; you may have read it. Anyways, everyone wants to be an expert and make claims without any 'real facts' behind their claims. This is exactly why I asked Dr. G this question. I trust, based on his experience and credentials, the information he provides regarding this subject. I was not able to find any factual information on this subject on PPG's website. I prefer to get facts and not opinions, which is especially important when my customers are concerned.

[Anthony Orosco]

You did exactly right Brad, you came and sought information from a trusted source with the credentials to back it up. You're also right, everyone wants to be an expert on matters where they have maybe read only an article.

Yes I did read that thread and the information you posted up was great

The cool thing is that now when a client asks you about something along these lines you can now give them an informed and educated reply.

Anthony

[thrasher]

Hi Dr. G & Anthony,

I am a new member from Indonesia. Sorry to revive old thread. I just happen to repaint three panels of my wife's car due to accident. Could you please elaborate which Optimum products are water-based hence safe to be applied to these panels after the car is returned? I found confirmation from Dr. G above that Optimum Car Wax is safe. Are products like Optimum Polish & OID safe to these panels?

Sorry for the questions. I am complete blank when it comes to chemistry

Many thanks for the response