Sealant makes chipping worse?

T

TANTO

New member
Joined
Jul 29, 2011
Messages
30
Reaction score
0
Some time ago i saw a thread somewhere on Sealants making paint seem to chip more easily. Normally i would poo poo this, but i did just get back into sealants, did my wifes late model Acura, took what i thought was a very minor gravel hit in the nose and now have 50-100 tiny chips on the hood and all the way back to the mirrors. Any truth to this conspiracy theory? I don't want to mention the sealant as i'm sure there is no non destructive way really know. TIA
 
Whoa I never knew about this before. I'd really like to find out if it's true because that would be quite scary.
 
woah! to be honest I have heard the opposite about sealants. But was the it ever resprayed or in an accident? or is it OEM?

Well part of it could be down to the stones that hit your car too. It will be a joy to fill them all! :bestwishes:
 
late acura's had clear coat problems. Could be a reason why.
 
Sounds to me like bad paint job, more than a sealant aiding in a rock chip, don't see how a sealant could do that to be honest.
 
This is something which is a result of excessively hard coatings. The modern trend in aftermarket protection is super hard coatings because they provide resistance to abrasion - there is little argument about that. Unfortunately this is only one piece of the puzzle. With a regular sealant or coating, the surface is (relatively) soft. Abrasion results in minor damage, likewise a stone impact will leave a mark. With a hard and brittle coating, the mild abrasion does nothing but, if the force is larger, such as stone impacts, it will go beyond the plastic limit of the coating. Think of comparing plastic with glass - plastic will mark, glass will smash. So the hard coatings are extremely strongly bonded to the surface so when the smash/shatter when subject to adequate force, they will rip apart the surface they are bonded to. This behaviour is actually well known from the wider coatings industry.

So the summary is that very hard coatings are excellent for abrasion resistance, resistance to swirling etc. but they are more prone to stone chipping.

I would be very interested in seeing the coatings guys address this - to my knowledge, the fight is almost exclusively about who produces the hardest... but the elasticity and plastic behaviour is (IMO) crucial.

ps. This is not appropriate to traditional sealants, they do not bond strongly enough to give this problem.
 
Mr Megane said:
This is something which is a result of excessively hard coatings. The modern trend in aftermarket protection is super hard coatings because they provide resistance to abrasion - there is little argument about that. Unfortunately this is only one piece of the puzzle. With a regular sealant or coating, the surface is (relatively) soft. Abrasion results in minor damage, likewise a stone impact will leave a mark. With a hard and brittle coating, the mild abrasion does nothing but, if the force is larger, such as stone impacts, it will go beyond the plastic limit of the coating. Think of comparing plastic with glass - plastic will mark, glass will smash. So the hard coatings are extremely strongly bonded to the surface so when the smash/shatter when subject to adequate force, they will rip apart the surface they are bonded to. This behaviour is actually well known from the wider coatings industry.

So the summary is that very hard coatings are excellent for abrasion resistance, resistance to swirling etc. but they are more prone to stone chipping.

I would be very interested in seeing the coatings guys address this - to my knowledge, the fight is almost exclusively about who produces the hardest... but the elasticity and plastic behaviour is (IMO) crucial.

ps. This is not appropriate to traditional sealants, they do not bond strongly enough to give this problem.
Click to expand...

Thank you Sir...for expressing these thoughts, and your insight.

-I, too, have had (and put forth) similar 'questions' in some of my previous posts regarding these issues...
Though not as perfectly elucidated as you have presented for discussion.

:)

Bob
 
So the summary is that very hard coatings are excellent for abrasion resistance said:
This was what i had heard way back when sealants first came out, although i had forgotten all about it. The car is a 2009 RDX with low miles, not been repainted. I know of no problems with late model Acura clear coats. I'm hesitant to say the product was Menzerna Power Lock as i sort of slurred them already on application issues. I do love PL though and am heart broken over this. The RDX was perfect and i was getting ready to put in on my black NSX. Looks like i might also regret trying QD on my mini-van!

So i guess this begs the question of which sealants are soft and which are (too) hard. I imagine the Mfgr's will be quiet on this. This would be so hard to flesh out, even for a good lab.
Click to expand...
 
I think what Mr Megane was trying to say is that coatings, such as opti coat, may cause the brittleness that can contribute to rock chips, not normal sealants. Correct me if i'm wrong?
 
Speed-Dude said:
I think what Mr Megane was trying to say is that coatings, such as opti coat, may cause the brittleness that can contribute to rock chips, not normal sealants. Correct me if i'm wrong?
Click to expand...

That's what he was saying....alright, I can't take it anymore...I'm sorry, that's a bunch of BS. Sealants have no measurable thickness, and the coatings, I think the thickest is Opti-Coat which is what, 1 micron? So if I put 1 more micron on my 50 microns of clear, I all of a sudden have a chip-prone finish??

If the OP can get 50-100 chips from a "very minor gravel hit", I'd had to see what a major hit would do. Paint chips when you get stuck on the highway behind a dump truck with a leaking gate (ask me how I know), and there's nothing minor about it. Unless it was the magic stone that killed JFK and bounced 50-100 times on the same car.

Cliff Notes: "minor gravel hits" don't cause 50 chips, unless you have 25-50 pieces of gravel, and coatings don't lead to more stone chips, more stones lead to more stone chips.
 
Setec Astronomy said:
That's what he was saying....alright, I can't take it anymore...I'm sorry, that's a bunch of BS. Sealants have no measurable thickness, and the coatings, I think the thickest is Opti-Coat which is what, 1 micron? So if I put 1 more micron on my 50 microns of clear, I all of a sudden have a chip-prone finish??

If the OP can get 50-100 chips from a "very minor gravel hit", I'd had to see what a major hit would do. Paint chips when you get stuck on the highway behind a dump truck with a leaking gate (ask me how I know), and there's nothing minor about it. Unless it was the magic stone that killed JFK and bounced 50-100 times on the same car.

Cliff Notes: "minor gravel hits" don't cause 50 chips, unless you have 25-50 pieces of gravel, and coatings don't lead to more stone chips, more stones lead to more stone chips.
Click to expand...

I certainly never suggested anything about 1 impact giving multiple chips.

As for your other comments, thickness counts but is also a red herring. If the bond between the sealant/coating and the paint is stronger than the bonds within the paint then if the coating happens to get ripped off, the paint will tend to follow. The thickness counts because it will be a parameter in the defining of the elasticity however one should not make the mistake of thinking a micron is negligible (in the grand scheme). If you think about the molecular structure, individual bond lengths will be of the order of hundreds of picometers (say 10^-10m). If your coating is a micron, this would result in something of the order of 10^4 layers (ten thousand layers). Even the nanometer level coatings will tend to be something like 100nm which will equate to about 1000 layers. These are not at all insignificant.

In any case, I know better than arguing scientific details on here - it is up to the reader to choose if they will think through the discussion presented or simply dismiss it based on some other experience. I would recommend anyone interested would have a ready through some of the many coatings publications on this topic.
 
so if you have a hard head and the window is down and you get hit in the head will you get chipped off ?
 
Chances are this stems from Acuras (and Hondas) historically having very soft paint, not the sealant itself. The clear coat is not "hard" enough to protect against stone chips compared to something like a Corvette or an Audi.
 
Mr Megane said:
As for your other comments, thickness counts but is also a red herring. If the bond between the sealant/coating and the paint is stronger than the bonds within the paint then if the coating happens to get ripped off, the paint will tend to follow. The thickness counts because it will be a parameter in the defining of the elasticity however one should not make the mistake of thinking a micron is negligible (in the grand scheme). If you think about the molecular structure, individual bond lengths will be of the order of hundreds of picometers (say 10^-10m). If your coating is a micron, this would result in something of the order of 10^4 layers (ten thousand layers). Even the nanometer level coatings will tend to be something like 100nm which will equate to about 1000 layers. These are not at all insignificant.
Click to expand...

I'm sure that everything you said is true and accurate. However, let's get out from under the electron microscope and into the real world--a chip is a chip. If my Opti-Coated car gets chipped, it's not because it was Opti-Coated, it's because a rock hit my car. If the chip is 100 microns bigger than if I didn't have Opti-Coat...I still have a chip...it's just an unnoticeable amount bigger...and I still have to touch it up or live with it.

I'm sure if it was a noticeable effect, we'd have a ton of threads complaining about it. At the end of the day the advantages of a coating outweigh the disadvantages--FOR THE PEOPLE WHO WANT TO USE COATINGS.

As I always say, if you want your car to stay perfect, with no rock chips, door dings, etc.; LEAVE IT IN THE GARAGE.
 
Setec Astronomy said:
I'm sure that everything you said is true and accurate. However, let's get out from under the electron microscope and into the real world--a chip is a chip. If my Opti-Coated car gets chipped, it's not because it was Opti-Coated, it's because a rock hit my car. If the chip is 100 microns bigger than if I didn't have Opti-Coat...I still have a chip...it's just an unnoticeable amount bigger...and I still have to touch it up or live with it.

I'm sure if it was a noticeable effect, we'd have a ton of threads complaining about it. At the end of the day the advantages of a coating outweigh the disadvantages--FOR THE PEOPLE WHO WANT TO USE COATINGS.

As I always say, if you want your car to stay perfect, with no rock chips, door dings, etc.; LEAVE IT IN THE GARAGE.
Click to expand...

Mr Megane - As a retired engineer i'm thrilled with microscope data and thank you much for your input. Could one find these industry pub's? Setec - I agree with your logic of a chip is a chip, but my read from Mr M is there may be bunches of tiny chips that would not have chipped at all if this hard layer had not shattered above it. Seems logical even without the microscope. Surely you have pulled off paint after leaving tape on too long(?). I think we will find out as Mr M says that this is a well know thing. As far as people complaining, there is no way anyone would know. If i had not sort of remembered that this was an issue years ago, i would have just assumed that the hit was much bigger than i thought. And the sealant may well not have been an issue in my case. It's a discussion. If analytical spitballing is not your thing, just let us BS'rs BS. An old engineering group saying is that "one empirical test is worth 100 expert engineer opinions" so i understand not getting lost in the weeds. I have a door to test on, but reading the industry papers is the short cut to the truth IMO. I will see what i can find.
 
TANTO said:
Mr Megane - As a retired engineer i'm thrilled with microscope data and thank you much for your input. Could one find these industry pub's? Setec - I agree with your logic of a chip is a chip, but my read from Mr M is there may be bunches of tiny chips that would not have chipped at all if this hard layer had not shattered above it. Seems logical even without the microscope. Surely you have pulled off paint after leaving tape on too long(?). I think we will find out as Mr M says that this is a well know thing. As far as people complaining, there is no way anyone would know. If i had not sort of remembered that this was an issue years ago, i would have just assumed that the hit was much bigger than i thought. And the sealant may well not have been an issue in my case. It's a discussion. If analytical spitballing is not your thing, just let us BS'rs BS. An old engineering group saying is that "one empirical test is worth 100 expert engineer opinions" so i understand not getting lost in the weeds. I have a door to test on, but reading the industry papers is the short cut to the truth IMO. I will see what i can find.
Click to expand...

A google is generally the best first bet but the terms for your search would be 'brittle', 'fracture', 'crosslink density' or similar. As you may well have spotted already on your searching, higher cross linking more or less means increased hardness but excessive level lead to embrittlement. Most of the literature is related to more traditional clear coat and paint technologies but the fundamentals are the same. Take it to extreme and you have to ask yourself why the clearcoats are not made super super hard - often there is plenty of room to increase crosslink density. As you say, this is a thought experiment and all I am saying is that hardness alone is not enough.

Now you should not interpret my words as 'coatings are bad'. If the product is done correctly, my words may very well not apply. BUT I have heard enough discussions about supergard or gard-x and stone chips to make me wonder.
 
I'm not buying that a sealant, wax, or even a coating is going to have any effect on stone chipping being worse or better, but if someone wants to shoot Dr. G an email I'm sure he can answer this question for you.


FWIW, My Acura chipped just as much with and with out Opti-Guard.
 
I find it difficult to believe that a hard coating on paint can increase the incidence of chipping. It seems to me that a harder coating on a softer base is like case hardening on metal to make the surface harder, without hardening the metal throughout, so that the entire part does not become too brittle.

A well made sword, like a Samurai sword, is hard on the outside so that it can hold an edge, yet is springy on the inside so that the blade can flex instead of breaking.
Part of how the best swords can do this so well is because of layering harder metals around softer ones.

I have heard however, that sealants that contain silicone can make touching up paint more problematic, because the silicones are absorbed into the paint, causing new paint not to not stick properly. That was the big concern in the 80's when sealants first started becoming popular.
 
It is hard to give realistic macroscopic analogies... that is the thing with the microscopic and nanoscopic world - the behaviour is often not as one would expect from macroscopic world experience.

The best one I can think of on the bonding on the surface is superglue on your fingers. What happens when you rip your fingers apart? You rip the skin off at the same time. I realise that this is a totally different scenario but fundamentally you are applying a force larger than the shear strength of the system and you are causing a whole load of damage to the underlying area. Had you been using PVA glue, the glue (or top coating by analogy) would have been ripped apart whilst the underlying would have been OK.

For background, I am a chemical manufacturer, I formulate new products like most people eat snacks, my initial education and doctoral studies were in atomic and molecular physics and I have also studied and published for a time in silicon and semiconductor surface modification. Not to say I cannot get it wrong... but if you are interested in learning, don't dismiss my thoughts without taking the time to reason through and do a bit of reading on the topic.

I'll shut up now!
 
You must log in or register to reply here.
Back
Top