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Have I Just Killed My Paint ?


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#1 digitalfriction

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Posted 10 April 2011 - 08:02 AM

my mini bodyshell has never had its paint properly flatted, It wasnt painted by me, I bought it as a painted bodyshell. Now the weather has picked up I thought I would try and get it looking better.

I did the following:

1) wet sand with 800 wet and dry
2) wet sand with 1200 wet and dry
3) wet sand with 1500 wet and dry
4) rub with rubbing compound
5) rub with t-cut colour
6) polish with Autoglym super resin polish

all seemed fine, I have just gone out this morning (8.30am still cold)

and the paint has DIMPLES !!!!!!

Posted Image
Posted Image

when I was sanding it was coming off white, so I assume it was a clearcoat?


What has happened ???!?!??!?!?

#2 myredmini

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Posted 10 April 2011 - 08:56 AM

Normally you just flat off with 1500 or 2000 grit straight away as 800 may be a little harsh on it for flatting. By the looks of it when it's been painted the bodywork has not been prepped properly and those blisters have began coming through. I have been told when painting, if doing it in your garage is to make sure it's prepped right, clean with panel wipe and put a heater in the garage to get it all dry and warm. If you paint in cold damp weather this is when problems arise.

Hopefully someone can expand on this issue a bit more.

Dan :)

#3 digitalfriction

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Posted 10 April 2011 - 09:10 AM

Normally you just flat off with 1500 or 2000 grit straight away as 800 may be a little harsh on it for flatting. By the looks of it when it's been painted the bodywork has not been prepped properly and those blisters have began coming through. I have been told when painting, if doing it in your garage is to make sure it's prepped right, clean with panel wipe and put a heater in the garage to get it all dry and warm. If you paint in cold damp weather this is when problems arise.

Hopefully someone can expand on this issue a bit more.

Dan :)


I have no idea how it was painted, or what with?

I dont think it can be how it was painted, the dimples have only appeared on the section I have rubbed and polished. I have tried to rub it down again, and I have got rid of the dimples, however I think the clear coat was way too thin, as it has rubbed through on a 1" area.

I think I will have to go for a respray, any other suggestions?

#4 mike.

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Posted 10 April 2011 - 10:27 AM

Thats microblistering, its a killer.

Its from moisture or a reaction under the paint expanding.

My car has been plagued with microblistering, had my car resprayed twice now and i'm still seeing signs of it. Only way to get rid of it for sure is a bare metal respray.

Also i'm not surprised you rubbed through using 800 grit paper, thats pretty harsh for flatting. I would of started with 1500 if it were me.

Edited by mike., 10 April 2011 - 10:29 AM.


#5 digitalfriction

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Posted 10 April 2011 - 12:59 PM

Thats microblistering, its a killer.

Its from moisture or a reaction under the paint expanding.

My car has been plagued with microblistering, had my car resprayed twice now and i'm still seeing signs of it. Only way to get rid of it for sure is a bare metal respray.

Also i'm not surprised you rubbed through using 800 grit paper, thats pretty harsh for flatting. I would of started with 1500 if it were me.


Any ideas why its come up just on the area I have worked on?

I have managed to blend in the patch where I rubbed through, very difficult to spot now.

Am I likely to be ok spraying over what is already there, seeing as the microblisters have only showed when Ive thinned the paint down?

#6 digitalfriction

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Posted 10 April 2011 - 01:24 PM

Thats microblistering, its a killer.

Its from moisture or a reaction under the paint expanding.

My car has been plagued with microblistering, had my car resprayed twice now and i'm still seeing signs of it. Only way to get rid of it for sure is a bare metal respray.

Also i'm not surprised you rubbed through using 800 grit paper, thats pretty harsh for flatting. I would of started with 1500 if it were me.


Any ideas why its come up just on the area I have worked on?

I have managed to blend in the patch where I rubbed through, very difficult to spot now.

Am I likely to be ok spraying over what is already there, seeing as the microblisters have only showed when Ive thinned the paint down?

I've been back out, and all the remaining microblisters have gone, it must be the heat of the sun, can I stop them showing again?

#7 JoneseyBoy

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Posted 10 April 2011 - 02:43 PM

Did u paint it your self or did u buy it already painted. If you painted it and its fresh laquor 800 is far to course and there is no need to use anything below 1200 on laquor anyway unless you really know what you are doing. If you brought it and this was its paint job then you shouldn't wet flat it as you don't know how much laquor is on it and how much has previously been rubbed of.

You can't just paint this you are going to have to rub it all down and prime it. If you paint it the thinners will get under the laquor were you have broke threw and cause a reaction.

#8 digitalfriction

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Posted 10 April 2011 - 03:13 PM

Did u paint it your self or did u buy it already painted. If you painted it and its fresh laquor 800 is far to course and there is no need to use anything below 1200 on laquor anyway unless you really know what you are doing. If you brought it and this was its paint job then you shouldn't wet flat it as you don't know how much laquor is on it and how much has previously been rubbed of.

You can't just paint this you are going to have to rub it all down and prime it. If you paint it the thinners will get under the laquor were you have broke threw and cause a reaction.


As I said in the first post, I bought it already painted. I have figured that 800 was too course, and I didnt rub through using 800, please read my posts, as I explained using 800 then 1200 then 1500 then compund then polish seemd fine, but in the morning there were blisters. I rubbed the blisters down with 1500 and soapy water and I broke through. My question about painting over did not mean just the one inch area where I broke through, I was talking about the whole car. I have already blended the area I broke through, it isn't visible.

Again, going back to post 1, I didnt know it was laquered, I dont know what sort of paint, I just know that it had not been flatted.

If I cant just paint over it, can someone please explain why the blisters are only on the one area I have rubbed down? Surely the blisters are showing due to the thickness of paint, so adding more paint, and thickening the layer will hide them even more? I would be covering with cellulose, as that is all I have experience of spraying.

Edited by digitalfriction, 10 April 2011 - 03:26 PM.


#9 sonikk4

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Posted 10 April 2011 - 06:07 PM

I sprayed my wife's old mini with celly about 14 years ago in my garage in the middle of summer. I used a decent spray gun, had a decent moisture trap and a reasonable compressor. I followed all the rules or so i thought and once the job was finished the car look good. However come the winter time i noticed pimples starting just about everywhere so knew somewhere along the respray process i had messed up.

I have been told its moisture in the air or from the compressor, how true this is i am not sure but whatever it was it knackered the paint so that was that. We chopped the mini in like that and i do know the garage that bought threw a load of paint on it to hide it so some poor person bought it like that and i have no doubt in my mind it would have reappeared.

Pm panelbeaterpeter he may know a way with dealing with it.

#10 vix

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Posted 10 April 2011 - 07:58 PM

This is Dave, Vickys Husband.

I build streetfighters and paint them personally for each customer. (23 yrs experience)

The pictures show blistering which is BETWEEN the primer coat and Base Coat OR base coat and CLEAR coat.

The reason that they are now showing up is because you have sanded and polished the area in question. What happened is that you have both thinned the area there and also put frictional heat through the paintwork warming the paint work faster than the metal underneath can react. added to the fact that the area you did is now being warmed by the sun, its unfortunate that its going to show.

Now normally on a PROPERLY painted area this will not make a BLIND BIT OF DIFFERENCE, but the paintwork done on your vehicle wasnt the best.

Firstly, either there was excess moisture in the air when it was painted or the paint was applied with a gun being fed with UNDRIED air.

When painting the air supply should always be fed through a simple Drier or water trap (although watertraps are no as effective, especially when theyre left to fill up!!)

If paintwork is being done in a place that cannot be heated to dry heat and evacuated to remove moisture, then its best to do a couple of things.

1: try to warm the room/building/toilet/shed as best as possible, a few hours BEFORE paintwork commences.
2: Stick to moderately warm days, so that inherant moisture from DAMP days or EXCESSIVELY WARM days (they produce humidity)
3: make sure that every layer of work is cleaned and dried prior to work commencing.

Now that all doesnt HELP you, but hopefully explains WHY and what NOT to do when painting bodywork.

With the problem you have, youre KINDA stuck. Normally the moisture that is causing the blister show is buried, and regardless what ANYONE says, DO NOT burst them or continue to sand and buff.

Many people have tried to HEAT them away, Dont work! Some have tried to heat from the back side, thinkiing it will evaporate....Where is it going to go? Its blistered already, due to the expansion of gasses in the moisture, so heating it will just do it agaiin.

MY ADVICE.

Leave it alone. With a little luck, the normal heat from the sun will not bring it back out again, but I would imagine it WILL show up again. dark colours tend to be worse than light.
The only sure fire way to get rid of it is to refinish the panel.


Sorry if thats not the result you wanted but thats the way it is.

#11 JoneseyBoy

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Posted 11 April 2011 - 02:00 AM

Did u paint it your self or did u buy it already painted. If you painted it and its fresh laquor 800 is far to course and there is no need to use anything below 1200 on laquor anyway unless you really know what you are doing. If you brought it and this was its paint job then you shouldn't wet flat it as you don't know how much laquor is on it and how much has previously been rubbed of.

You can't just paint this you are going to have to rub it all down and prime it. If you paint it the thinners will get under the laquor were you have broke threw and cause a reaction.


As I said in the first post, I bought it already painted. I have figured that 800 was too course, and I didnt rub through using 800, please read my posts, as I explained using 800 then 1200 then 1500 then compund then polish seemd fine, but in the morning there were blisters. I rubbed the blisters down with 1500 and soapy water and I broke through. My question about painting over did not mean just the one inch area where I broke through, I was talking about the whole car. I have already blended the area I broke through, it isn't visible.

Again, going back to post 1, I didnt know it was laquered, I dont know what sort of paint, I just know that it had not been flatted.

If I cant just paint over it, can someone please explain why the blisters are only on the one area I have rubbed down? Surely the blisters are showing due to the thickness of paint, so adding more paint, and thickening the layer will hide them even more? I would be covering with cellulose, as that is all I have experience of spraying.



no need to be rude is there buddy your the one that needs help not me.

the cause of this is because who ever sprayed it didnt allow it to flash of proply wich stops the solvents evaporating. in the end they just break threw the surface and cause microblistering but youve just made the process quicker and helped it get to the surface by making it thinner. like i said before the only way to sort this is to take the paint all the way down prime and repaint it. youll find that the hole car will go like this when the cold weather hits but the blisters will disapear in the heat. also youll never match the paint if you paint it in celly as the rest of the car is based and cleared.

Edited by JoneseyBoy, 11 April 2011 - 02:21 AM.


#12 digitalfriction

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Posted 11 April 2011 - 08:09 AM

Did u paint it your self or did u buy it already painted. If you painted it and its fresh laquor 800 is far to course and there is no need to use anything below 1200 on laquor anyway unless you really know what you are doing. If you brought it and this was its paint job then you shouldn't wet flat it as you don't know how much laquor is on it and how much has previously been rubbed of.

You can't just paint this you are going to have to rub it all down and prime it. If you paint it the thinners will get under the laquor were you have broke threw and cause a reaction.


As I said in the first post, I bought it already painted. I have figured that 800 was too course, and I didnt rub through using 800, please read my posts, as I explained using 800 then 1200 then 1500 then compund then polish seemd fine, but in the morning there were blisters. I rubbed the blisters down with 1500 and soapy water and I broke through. My question about painting over did not mean just the one inch area where I broke through, I was talking about the whole car. I have already blended the area I broke through, it isn't visible.

Again, going back to post 1, I didnt know it was laquered, I dont know what sort of paint, I just know that it had not been flatted.

If I cant just paint over it, can someone please explain why the blisters are only on the one area I have rubbed down? Surely the blisters are showing due to the thickness of paint, so adding more paint, and thickening the layer will hide them even more? I would be covering with cellulose, as that is all I have experience of spraying.



no need to be rude is there buddy your the one that needs help not me.

the cause of this is because who ever sprayed it didnt allow it to flash of proply wich stops the solvents evaporating. in the end they just break threw the surface and cause microblistering but youve just made the process quicker and helped it get to the surface by making it thinner. like i said before the only way to sort this is to take the paint all the way down prime and repaint it. youll find that the hole car will go like this when the cold weather hits but the blisters will disapear in the heat. also youll never match the paint if you paint it in celly as the rest of the car is based and cleared.


Sorry mate, I didnt mean to come across as rude.

I dont need to wory about colour matching, as with celly I would be changing colour anyway.

What I need opinions on is this:

as has been pointed out in the excellant replies above, there is a problem in the low levels of my paint. However they have only come to light because I thinned the paint down/caused heat.

I have tried on a different area a light rub down with 1500, and a light compunding and polish, and NO microblisters have appeared.

The appearance of the blisters is obviously to do with the thickness of paint, so if I lightly key the existing paint, and prime then colour change, all in celly. Am I likely to bury the microblisters in enough paint to stop them showing again (I have never seen them on the other panels that I have not touched !)

#13 JoneseyBoy

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Posted 11 April 2011 - 10:49 AM

If its because the solvents haven't evaporAted then then its not a good idea to try and bury it as they will still try to evaporate and cause blistering again. Am afraid its a full job again. That's standing all the paint of then priming then painting. That's what I would do but it is up to you.




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