DOES PAINT HAVE ABSORBENT PORES?

You read and here from these "miracle sealant" companies that their products absorbs into the paint.

Question? Does paint really have pores?

Thanks

24th December 2000, 14:35
Cen... does clear-coat have pores that open in heat? I'm learning and very interested so have patience with my seemingly dumb questions!

Bob
Centrate
24th December 2000, 16:02
No problem Bob. I am not really in a position to discuss this intelligently, but allow me to talk about it using my engineering background.

First, the "pores" that open are not necessarily "holes" on the surface. If you were to take a piece of material, i.e., leather and look at it using a microscope, what you'll see are different textures under room temperature and as additional heat is added. Heat excites molecules which causes materials to expand no matter how dense they are (same for wood, steel or concrete... this is why they intentionally put physical gaps on concrete pavements - to accomodate its larger size during the day).

Material expansion is the result of the increase of the distance between two or more particles that make up the material. The gap that is formed accounts for the change in texture, and it is the same gap that "traps" foreign materials.

This is the gap that we refer to as pores in this discussion. Since they are microscopically small, it is impossible to take out what's trapped within them. Once it cools and contracts, it becomes permanent.

It is the same analogy is a color dye. The reason it is able to color fabric is because the dye embeds itself between these "gaps" on the fabric.

To answer your question based from this train of thought, I assume that clears also have pores (or gaps) that open when heated, enough to trap wax particles and consequentially make them dull.

I hope that was helpful.


[This message has been edited by Centrate (edited 24 December 2000).]
RudeDude

WWich is why a "clearcoat" is important, as it becomes more "dense" as it cures, to a point.

Any vehicle, painted with todays modern paint systems will still absorb moisture into the paint system.

This is according to technical information I received during my decades of working with the vehicle manufacturers paint suppliers, be it PPG, DuPont, BASF or SherwinWilliams.

A couple of studies showed that the average 2 year old vehicle, with no wax or polymer sealant could absorb up to a pint of water on the horizontal surfaces following a wash or rain event.

This carries any pollutants, IE, acid rain components, for an example down into the clear, where heat and oxygen then do their part to activate, and make the absorbed caustics reactive.

Much as when you spill a small amount of some acids on your cotton clothing, it may show little or no effect until the article of clothing is washed(warm or hot water, surfactants are present) , and then the damage is clearly shown.

This is termed "reactivity", and goes on each day, affecting almost all substrates.

Ozone in metro areas is another culpurit, like in LA, NYC, etc, and hot days, when a vehicle's paint surfaces are hot, some air borne particles are on the paint, a small micro burst showers comes through and produces "water spots", which may actually be "acid rain" deposits.

Anti-corossive resins, such as in a quality polymer/acrylic paint sealant will aid in warding off or reducing such damage, due to the amino-functional qualities of such products, plus their "high fracture point" when subjected to heat.

I wrote a technical article on this several years ago, and was published by a couple of the carwash magazines. The contributing engineers were noted at the end of the article, from Ford, PPG, etc.

Want to actually see the water go into a paint system?

Take any non-clear red vehicle, put a few drops of water on it and observe in a few minutes the presense of a "color change" where the water was placed.

With a few minutes of normal 70 to 90 degree heat, they start to disappear, however a percentage of any contaminates that were present, and liquified, is now down in the red paint systems, waiting for more moisture and some heat to activate their chemical reactivity.

Ketch

SEM makes the claim that all their prep products for repair and refinishing gravitate into the paint pores and flush contaminants to the surface
I'd say that thermoset paints dont have the same pore structure or amount of pores that the old paints of 30-60 years ago did

Hi Ron - you mentioned that paint sealants reduce damage, but it almost seems that if water can and does have the ability to absorb through the clear and base(thus the need for e-coat/corrosion protection), it can also easily penetrate through the sealant. On humid rainy days I've experimented by sealing a bare piece of metal and left it outside overnight to find them already atarting to corrode the following morning. Can you explain how the sealant helped in this situation?

Following this post, and not being an "expert" in automotive paint I contacted a chemist that I know whose company is in the automotive paint business and asked him to read the posts herewith. Here is what he states:

"Reading the posts it appears that some posters have a little knowledge, which can be dangerous, as they say. Some of what people say is partially true, but much of what they say is way beyond fact. They add a bit of fact and then turn the fact into an essay."

From my experience as a chemists who formulates automotive paint and who has developed car care products for paint protection. I would hope that would give me some creditability to express my opinion.

Here is the issue with automotive paint. What I say comes from our experience working within the paint laboratores of the major paint manufacturers. And, we REALLY do know what we are talking about. Our company alone manufacturers over 80,000 colors of paint, all of the primers and all of the clear coats.

Personally, I am now working on improving the corrosion resistence of all our primers, DTM, urethane, ane epoxy. To do this you MUST understand how paint functions to be able to do this work.

That said, paint do have an irregular surface. They should not be referred to as "pores." However, they are "not holes" that extend from the surface of the paint to the substrate. No surface is 100% flat. Therefore anything you put on the surface can find it's way to the bottom of the surface irregularity.

Also, paint is not 100% waterproof, therefore any liquid put on the surface (including water) can ABSORB into the paint.

Also know that paints have fillers in them which can absorb water (or any liquid) into the paint film.

The resins and fillers used in today's paints are much better at preventing absorbsion, but not completely.

My work at present involves the use of additives and filler combinations that are less absorbent and also improve adhesion. Therefore with less absorbtion and better adhesion you improve corrosion resistence and the paint will last longer.

Anything then that you put on the surface of the paint to prevent this "absorbtion" will be of long term benefit to the paint."

Regards
Bud Abraham

I also bounced this thread off of my contact that also has a direct involvement in the OEM paint industry as well as a manufacturer of a well known detailing line and whom which holds a Doctorate degree in Polymer & Organic Chemistry. Here’s what he mentioned about the subject:

"Hi David,

Thank you for the link. I agree with what Ketch says for the most part. At the molecular level water is much smaller than wax or pigments as well as nearly all other chemicals for that matter (the only chemicals that are smaller are Hydrogen gas and Helium). Water does penetrate into most polymers and substrates (not metal). Paint however retards that tremendously so you get a few molecules that come in contact with the painted substrate.

Most cars are made with stainless steel so they should not rust even though they do (316 gauge would not rust but 304 does). Paints that are manufactured for use on other metals contain corrosion inhibitors to prevent corrosion. I hope this helps. Thanks"

Quote
billd55
I am not really in a position to discuss this intelligently, but allow me to talk about it using my engineering background.


To answer your question based from this train of thought, I assume that clears also have pores (or gaps) that open when heated, enough to trap wax particles and consequentially make them dull.

While this person does admit to having an engineering background, I'm not sure if I can take their statement as nothing more than speculation w/o knowing whether or not their background is in an Automotive and/or Coatings environment.

Pro-Techt

Use a little common sense here.It is fine to question things that people say.
Although, do you need a expert to tell you that that paint breaks down from the
sun, water, and elements. If they did not, clear coats would last forever and require little or no maintenance.