The Stovebolt Site Forums The Shop Area Paint and Body Shop Rings appear after painting

A few days ago I started repair on a hail damaged roof. I sanded it down with 120 grit, filled the dents with Evercoat Metal Glaze, sanded that down, and finished with 220 grit. I sprayed with a surface prep, let dry, and sprayed 3 coats of a 2K urethane surfacer (with 10-15 minutes flash between coats). I let it dry for about 3 hours, blocked it out with 220 and 320 like in the past, then surface prepped and 2 more coats of primer were put on. I let that dry, blocked with 320, 400, and 600. A couple days later, I surface prepped and sprayed with Dupont chromabase in black, let that flash for 1/2 hour or so, and sprayed with 2 coats of clear. I went back to look 1/2 hour after spraying and noticed that every spot that had filler, now shows up as a ring under the paint. I find this strange, as it never showed through when it was in primer, and it felt perfectly smooth. Any ideas why this happened or how to fix it?

Sounds like your filler absorbed your primer and paint. Does it look duller too?
Scott

as it has set up over the day you can see every sand scrach now even under the primer

Parts guy, when you say "surface prep" are you are refering to a "wax and grease remover"? If you are that may be part of the problem. A "surface cleaner" shouldn't be "let dry" as you did. It is put on wet and wiped off WHILE wet. If this is the case it is likely your surface cleaner was soaked up by the filler and or edges of the feather edges paint surounding the repair. This solvent was then trapped in the sand scratches and even possible under the edge of the filler and or feather edge. The primer you applied added more solvent, then sanding the urethane and applying more, added more yet.

On a horizontal surface like that roof we have a tendency slow down and apply too much material, it is just human nature to apply more material here than say on the side panels. So, you likely built up too much material that wasn't fully cured to begin with, coupled with the trapped surface cleaner, there was a bunch of solvents that just didn't get out before the surface flashed off and started to cure. That solvent was trapped and then when the color and clear was applied it too softened the area and it shrank down. In the text below I discribe it in the use of these products in more detail.


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"Basics of Basics" Surface cleaners aka "Wax and grease removers” By Brian Martin

They are commonly called “Wax and Grease Removers” but many manufactures have changed the name to “Surface Cleaners” or similar names. I think the biggest reason is because the name “Wax and grease remover” implies that they will actually clean all of the wax and grease off the surface. The other reason for a name change is the simple point that wax and grease are only a few of the contaminants that you battle against while painting.

The basic idea behind these cleaners is simple, they are designed to lift the contaminant up off the surface long enough for you to wipe it away. The surface MUST stay wet and HOLD those contaminants up in the cleaner for you to wipe off with a clean/dry rag. That is mistake most make, they let it dry and the contaminant ends up laying right back on the surface. First of all let’s clear up a few things; Lacquer thinner, acetone, MEK, and enamel or urethane reducers are NOT surface cleaners. Lacquer thinner evaporates too fast and doesn’t give you time to wipe it off wet. It is also much to strong a solvent for most cleaning and can get under the edges of sand thrus or soften substrates. Enamel and urethane reducers often have resins and other components in them that are designed to be added to the product they were INTENDED to be used with. To put it in a nutshell, buy and use the products recommended by the manufacture of the paint SYSTEM you are using. A gallon of the proper surface cleaner runs about twenty or twenty five dollars it is money well spent. The gallon will last you through many projects, a few cars even. The pint of paint or clear to do one small redo will cost more than that.

I checked on our paint dept. at work to see how much surface cleaner they go through. We do between 100 and 150 cars a month and purchase three to five gallons of surface cleaner. We purchase about $12,000 a month in paint materials and only about one hundred bucks of that is surface cleaner. So that being said, at that rate a gallon should last a home hobbyist a lifetime, so buy the right product for the job.

One reason we use so little is how we use it. Here in the San Francisco bay area with strict VOC rules we are not allowed to pour the surface cleaner out onto a rag. We have to spray it out of a spray bottle. Like most things we are forced to do, we resist. But it has turned out to be a great way to use this product. You should give it a try, it works real well. You spray the panel and then wipe it off.

I like to have lots of clean rags when I am doing paint work. Clean rags are one of the most important item you can have in a shop. In the last few years this has gotten much easier to do. I remember having a can of paint covered rags in the corner, thinking I could wash them. I would wash them and they would be clean but the dried paint on them would be hard and make the rags unusable. Then of course you don’t want to wash them in your home washer anyway, unless you want your wife’s bra to smell like enamel reducer.
Now a days the disposable rag is king. You can get a box of “rags” for a pretty fair price and just throw them way when done. You always have nice clean rags. They are not “just” paper towels, so don’t think that the “Mr. Cleanup” paper towels you get at the supermarket are going to do the job. Go to your paint store and get the real thing. There are many different kinds, from cheap wipes similar to your kitchen “paper towels” to lint free towels for final wiping. TORX products are available at NAPA auto parts and is one source for these towels. Again, yes they cost more money than washing rags or your wife’s “Mr. Cleanup” paper towels but what kind of money are you spending on your paint products?

So let’s go over exactly how you use it. As mentioned earlier, you need to keep it wet prior to wiping it off. The best way to do this is keeping your cleaning area down to a manageable size. I usually wipe no more than a half a panel at a time. About six square feet is all you can do without problems of it drying to fast, and even then you have to keep moving pretty fast. You just don’t want it to dry, if you do, you have wasted your time. You haven’t done what you intended to do, at all. It was not even close, you wasted your time.

[img]http://members.aol.com/goodstuff53/waxandgreasegraffic.jpg[/img]

When should you wipe the surface?
Well first of all, BEFORE you sand. If you don’t wipe the surface before you sand you will not sand off the contaminants, you will sand them INTO the surface. So a good cleaning before sanding is recommended. If the surface is really dirty, clean it a few times changing to clean rags every time. Remember, you want to wipe off the contaminants, so if you use the same rags on the subsequent wipes you can leave the contaminants you wiped off on the first wipe!

Wiping before applying primer or paint of course is also recommended. Broom and/or blow off the sanding dust (I have bench brooms for wood working that are fine bristled and work great). Be sure to use the proper cleaner and wipe it dry really well. Then be sure that any remainder has flashed off (evaporated) before applying your primer or paint. You don’t want any of the cleaner to be trapped under your primer or paint!

Have a few rags ready to go folded in fourths. Put the rag over the opening on the can of surface cleaner and give the can a “slosh” getting the rag wet, not too wet but wet. You don’t need to have it dripping all over the floor, but it should be good and wet. Get in the habit of wiping things down like you are painting it. Use a back and forth pattern with an over lap being sure to wet EVERY square inch. The entire area should be shiny wet, then switch to a clean dry rag and wipe it dry using the same “get every inch” procedure. If you feel it dried before you could get it off, repeat the cleaning. As a painter I worked under many years ago would make me repeat like a private in boot camp “YOU CAN NEVER GET A CAR TOO CLEAN, SIR”

Because the term “wax and grease remover” is thrown around so much little is said about the how different they can be. Until I had became a paint rep I didn’t even know there were different kinds. After painting for twenty years I had always just grabbed the “wax and grease remover” without a thought as to what I was using it on. When I bought a cleaner and found it worked different I just attributed it to the brand and not the fact that it was just not the type of cleaner I had been using.

Just like solvents you add to your paint products there are different “temps” cleaners. Not that they are to be used in different temp shops but that they flash faster or slower than another. This is important in that you don’t need a super slow flashing cleaner on your final wipe. Nor do you need a super fast one when you are doing your first wipe down of a greasy car prior to sanding.

There are also different “strengths” of cleaners. Some are designed for cleaning soft substrates like lacquer while others are much more harsh for cleaning enamel substrates. Most all of them “can” be used at most times but, there are some that are better than others for particular circumstances.

There are four common groups. I don’t have every cleaner listed here but this will give you a good idea at what is available.

1. A very slow evaporating cleaner. It is also very weak, and actually only mineral spirits or mostly mineral spirits. This does NOT mean you can go to the hardware store and buy their mineral spirits, for goodness sakes just but the high grade product from the paint manufacture. This is the type of cleaner is the most common found in the shop. It is a good cleaner because it is weak and will not attack any soft substrates like lacquer, uncured enamels, etc. But it will not clean a lot of strong contaminants like vinyl treatments. When you have a reason to believe there is a particularly bad contaminant you may need to go to a stronger cleaner. It is very slow evaporating so you have to be sure it is fully evaporated after wiping before you apply any paint product over it. Specifically those nooks and crannies, be sure it is good and gone before you apply any paint product. It gives you lots of time to wipe it off because it evaporates so slow.

Examples are:
Sherwin Williams R1K213, Martin Senour 6387, PPG DX330, DuPont 3939S, BASF 901.

2. This cleaner is fast and strong. It is commonly recommended as a “pre-cleaner” before sanding. It will attack some soft substrates like lacquer and uncured enamel but if you are using it before sanding you can correct that. It will clean the stronger contaminants like tar and unseen ones like silicone vinyl protectants.

Examples are:
Sherwin Williams R7K156, Martin Senour 6383, PPG DX440, DuPont 3919S, BASF 900.

3. This cleaner is a weak solvent with fast evaporation and is usually used just prior to painting, while the car is in the booth. It is very fast evaporating and is necessary in the production shop where you don’t have the time to wait for a cleaner like #1 to evaporate. It is perfect for this use, just getting those finger prints and dust residue off.

Examples are:
Sherwin Williams R7K158, Martin Senour 6384, PPG DX30, DuPont 3901S, BASF 901.

4. Because of VOC rules a waterborne solvent cleaner was developed. It is not needed in most of the country but it has been found to have an interesting use there. Because it has water in it (water and alcohol molecules share a common atom so they are a “link” between the water and enamel based solvents) it actually helps with static electricity. Washing the car with water is the best, but that can’t always be done.
It is also the recommended surface cleaner for plastic parts with many paint systems.

Examples are:
Sherwin Williams W4K157, Martin Senour 6388, PPG DX380, DuPont 3909 or 3949, BASF 905.

If you find that you have been using the “wrong” cleaner, don’t sweat it, it is not THAT critical. As I said, there are cleaners that work better than others in certain circumstances but few would be “wrong”.

I know of one particular mistake I made for many years. I was using one from the number 1 example. I used it all the time as I still do. The problem was I was using it wrong. Back in the days of lacquer primers and paint I had a few problems that I just couldn’t figure out, till years later that is. I would see a lacquer paint job I did a year or so later and there would be water spots on it, coming from under or within the paint. It looked just like you would have when you dry a car in the sun and the water would dry in the patterns that the wet towel left. I always knew it was the surface cleaner but just couldn’t figure out why it would happen. I now know that the cleaner was just too slow evaporating and some stayed on the surface to be buried under the paint. The lacquer primer soaked it up and held it. If I had waited a little while longer before painting or used one from the number 3 example I wouldn’t have had a problem.

Hopefully this info will help you choose the best cleaner for the job. But most off all, I hope it puts to rest all the “old husbands tales” of using thinner or enamel reducers as cleaners.

I have been using Tumbler silicone and grease remover. I spray it on about a 4 foot square section at a time, wipe it off and blow off any remaining moisture with my air hose. I do this before sanding down a panel, and after sanding the primer. I used the same stuff on my last paint job too and it turned out fine. I did two things different on this paint job. I used the evercoat metal glaze instead of my usual filler, and it was my first time using Dupont paint. I asked when I bought the paint if I needed to spray on a sealer first and they said I didnt need to. Would that have made a difference, or is it some other problem? Other than that, the paint looks good, shiny like a mirror.

"Something" in the way of solvents got under the edge of the filler and feather edge. I still think it was the primer being applied too heavy and not left to flash long enough.

Sealer would have just added more solvent to the mix.

I let the primer flash for 10-15 minutes between coats, it looked dry, and it sat for 2 days after sanding before I painted it.

So how do I fix this problem?

I have to tell you, if you applied a 2K primer and allowed it to flash properly, then left it for two days, it is INSOLUABLE and that is all there is to it. It would seal off ANYTHING. If you blocked it and the surface was flat, there were no signs of these "rings" than that is it, done deal. But SOMETHING wasn't done right along these lines.

Leaving the primer to flash and then leaving it to cure after doesn't GUARANTEE that the solvents have all flashed out.

Going back to the "wax and grease remover", if you are using a very slow flashing product it still could be soaking into the substrate. Blowing it with air is only flashing off what you can see, it may be still soaked into the substrate. I don't believe in using any cleaner on the sanded primer UNLESS you KNOW there has been some contamination. If you cleaned it before sanding, it is clean. You do want to use a FAST evaporating cleaner right before paint, but between primer coats it is not nessisary.

You are working on a roof, it is human nature to apply the primer or what ever heavier on a horizontal panel. If you applied your primer heavy, the flash time between coats is a moot point, there still could be trapped solvents. Then sanding and applying more primer in the same heavy coats, MORE solvent. The temp of the surface, the "temp" of the solvents you useing, the air movement in the room, these ALL are factors to solvent flashing as well.

I have to tell you, unless there is a mis-mixed problem where not enough hardener was used or something like that, this IS a solvent issue. Now, it this IS a solvent issue than you have to figure out what it is.

You may think you did everything like before, but you may be adding one more factor this time. I call it "alignment of the planets" That is when you are on the edge of the window on a number of different issues, WHAM, failure. You could be just a little slower on the gun movement, this in it's self isn't a problem. You shot it "Just like before" but this time there is a slightly slower solvent involved, PLUS, it is a little cooler than "before" when you had no problem. These three factors add up to the "planets being aligned" WHAM a failure.

You hardly ever do it "just like before", there is always SOMETHING different, be it temp or SOMETHING.

It could be as simple as applying two or three coats primer, letting it cure for a few hours (did you have at least 60 degrees during that time?) then "breaking it open" with 220 and leaving it til the next day. THEN block it and reprime. That right there could eliminate one of the "planets"

so how do i fix this i tryed wet sanding with 1200 and then 1500 still have to do the 2000 but it looks like it could be buffed back do you think this is the right way to do it or the wrong way. thanks for all your help on this and for things in the past

If you can see it thru the clear, sorry but you are stuck. You would have to sand and shoot some more base and clear.

Can you see ANY low spot or something like that in these "rings" or is it just a shrinking scratches you see?

it is just the shrinking scratches i have it flat again but i am wondering if it will peel in time or now that it is hard is that how its going to stay if so it will buff out

My first impression when reading the original post is that materials were applied too heavily, then sanded too quickly, and after reading the rest, I still think that's it.

Even with the speed of 2K primers, the solvents still need to evaporate out of the paint film, and the heavier the film, the longer the wait to get the solvents out.

The initial 3 coats of primer were only given about 3 hours to dry before sanding, and then 2 more coats were applied, making a total of 5 coats of primer applied within about 4-5 hours of time. Then, a couple hours later, it was sanded again with fine paper for paint application, THEN it was allowed to sit for 2 days.

It's my opinion that the repair shrank over those 2 days, and that's why you're seeing repair rings after paint application.

To me, it would have been better to let it sit for 2 days, and sand it for paint afterward.

Everything posted about cleaning solvents is 100% correct, but I don't think it was the issue this time.

My 2cents

Tim Bowers
Stellar Antique Auto Restorations

we had a talk with that paint guys and they said it was the factory finish on the car that is the cause of the problem

This "paint guy" either doesn't understand how to explain it or he is trying to put the blame on something else.

Please explain what it was that he told you. How did this "factory paint" CAUSE the problem? I am sorry, but he is off base on this one.

Please get an explaination of his idea, exactly WHAT the paint is doing.

Basically what the help tech guys said, was that because the scratches only showed up on areas where the factory finish was directly under the primer, that the scratches must be in the factory paint job somehow. They seemed to think that even if we just sprayed another coat of clear on the car's original surface (for whatever reason) that the scratches would have shown up. They were adament that there was nothing wrong with their product, that "somehow" the primer, base, and clear sprayed ontop, somehow softened into the factory paint. Yesterday we painted the hood also, it was fine for the first 8 hours or so, looked like glass so we thought we fixed whatever the problem was, then this morning we awoke to the same dilema of scratches showing up. I am getting very frustrated with the runaround everyone seems to be giving me, and the more I think about it, the harder it is to believe that the factory paint is the problem.

Parts guy, they told you EXACTLY what I did. There is NOTHING wrong with the product. There is nothing wrong with the old paint.

The problem is with the APPLICATION of the primer, color and or clear. You are applying it too wet and/or not letting it flash off long enough, period. That urethane primer will BURY and SEAL any scratches in the surface, I mean large scratches, it WILL bury them if the primer was applied properly.

Let's go over how the primer is mixed. What brand is it? What is the mixing ratio and what are the products you mixed to make the primer sprayable?

SOMETHING is shrinking down and it sounds like the primer, lets get to the nitty gritty here.

ok here goes. this is what we did on the hood.
It is ProForm 2K urethane primer surfacer. The mixing ratio is 4 parts primer to 1 part activator. The final sanding before priming was done with 220 grit. The primer itself was put on in 2 stages. starting around noon, first we sprayed a fairly wet coat, with a flash time of about 15 minutes, and then sprayed a little bit lighter coat. This was sanded with 220 then 320 9 hours later. Second stage of priming occured 2 hours later, spraying one coat, flashed for 15 minutes, and sprayed another coat. That was sanded with 320, 400, then 600 the next afternoon. The basecoat of color is Dupont Chromabase GM black (year 2000) using 7175S basemaker mid-temp activator-reducer. The mixing ratio is 1:1. Sprayed 1 coat, let it flash 10-15 minutes, sprayed 2nd coat, let it flash 10-15 minutes, and sprayed a 3rd coat. (they were all fairly light coats) The clear is Dupont ChromaClear 7500S, with 7570S reducer, and 7525 activator, with a mixing ratio of 8 parts clear to 2 parts activator to 1 part reducer. After spraying the base I waited 1/2 hour to spray the clear on, applying one coat, letting flash for 15 minutes, and then spraying the 2nd coat. That is all the spraying I did.

On the roof, we were talking about rings around a repair area. Are we talking about sanding scratches on the hood now?

Is 220 the roughest grit you are using?

How do you know for sure that each step of your sanding is taking out the previous scratch? Is there any chance that you are not getting out the deep scratches?

I like the description of the flash times/drying times on your hood repair better than how you explained the roof, anyway.

Just a guess, this time.

Tim
Stellar Restorations

Ok parts guy, first off, let me qualify my statments. I was a paint rep for a number of years. I did trouble shooting every day. Went to MANY courses and clinics all over the country in the subject of applying automotive finishes. I covered a territory in the second most populated area of California four hundred by one hundred miles in size. I represented 77 stores supplying thousands of shops. Watched, taught, helped, hundreds of painters. Ok, I don't know everything, and MORE OVER I am doing this without even verbal communication. So I'll take that into consideration.

First off, I have learned with a painter tells me a " first we sprayed a fairly wet coat, with a flash time of about 15 minutes" that he really means is a VERY WET coat that flashed five or ten minutes. Now, please, I am not calling you a liar, I am simply talking human nature and how we as humans think and act. MOST people don't see "wet" the same as the manufacture, believe me.

This primer is a low end product, NOT Dupont, right? I have never heard of the name. This can be an issue, it may not be TOTALLY "insoluable" when cured, "SOME" low end primers aren't, they just aren't that high of quality. For that matter, some high end urethane primers aren't as insoluable as others, but that is another matter.

You don't add solvent to this primer being the 4:1 ratio. That means there is no solvent temp choice for you, the primer has a "mid temp" solvent in it to cover many different spraying environments.
First question, what was the temp when you sprayed this "fairly wet coat"?

Second question, and you probably won't like this one either, but please explain exactly HOW you mixed the primer. What does 4:1 mean, what bucket or what ever did you use, if you mixed it in a single "bucket" was the sides of the bucket perfectly straight vertically?

Like I said, if I were in your shop looking at your car and material this would all be done much faster.

And you can believe in the thousands of trouble shooting calls I have been on, some pretty obvious things were found to be wrong so don't take it personal with seemingly insulting questions or comments I make.

It sounds to me like it is that first coat of primer. Either the quality, or the thickness applied with insufficient curing is causing excessive shrinking in scratches that may be too deep.

Normally those scratches would be filled with your successive coats, but with the shrinking you are fighting a losing battle.

Make that first coat much less heavy and extend the curing time before the second coat.

well i am folowing my tech sheets and i dont have the time to wait any longer the car has to be done by friday so i am going the wet sand with 600 today and reclear and hope for the best i guess unless you can say diff that its not a good idea

Scratches in anything but the clear coat will remain visible if they are visible now.

Parts guy, this is why I asked the questions. If you were following the tech sheets, there would be no problem. These questions, are just a few of MANY questions I have to ask to determine what happened. Without an honest discription of things like HOW did you mix it, I can't help you. Not, "I am following the tech sheet", but an explaination of exactly what that 4:1 means and how you mixed it. How many people do you think I talked to with problems when I was a rep said that..." I was following the tech sheets"? Come on, guess, I can tell you how many ALL OF THEM thats how many. Everyone always did everything right, that is why they had problems

If they did everything right, I had no reason for going over there right? No, I had to go over and see the shop, ask the question, look at their face when they told me, ask employees in the shop, basically be Columbo

I had the rep out at my shop before I was a rep, I told him the same thing I assume. But after all the questions were asked and answered he came up with the REAL reason and the REAL solution.

If you haven't got the time.......

A sign on the wall of one of the first shops I ever worked at back in 1979. It was a full on restoration shop where I worked on mainly 1933-1934 F 0RD (model 40's).

"Why is there never enough time to do it right, but always enough time to do it over"

well not to sure what caused the rings but wet sanding with 600 and re clearing fixed the problem but i still would like to know what the problem was so it dont happen again