VettePower

I brought my Vette back to the paint shop today to do a small punch list, as I had it painted a couple of weeks ago. This guy speacilizes in Vettes and did a great job. Like a mirror. Used the base/clear coat sytem from PPG.
Originally I had stripped the Vette all the way down to bare glass and then primered it with K-36. I then took it to him and he block sanded it and then shot it with DB40 primer/sealer before the final paints. He called me today at work and told me as he was glazing the car he has found a small area that seems to be blistering. What could be causing this, and is this something that will spread to the whole car??? I will be stopping at his shop on the way home. :sad:

VettePower

Any Painters out there???

lbell101

Could be caused by alot of things.
- Moisture or another contaminant absorbed in the fiberglass.
- Moisture or another contaminant left on successive primer or paint coats.
- moisture can also permeate the film while drying if in water or high humidity before full cure.

Finding out how far down the blister occured (at fiberglass, primer coat, paint coat) will help determine where the contaminant was left.

I'm sure there are other causes as well.

VettePower

What are the cures??? :eek:

UK Phil '78

I'm no expert in this field, but I read somewhere once that blistering is caused by moisture trapped between the fibreglass and the paint during the painting process. (somebody feel free to correct me if I'm wrong).

Apparantly, the moisture can also get in via the underneath of the fibreglass, so it's wise to treat the bits you can't see as well as the bits you can.

Not sure if it will 'jump' across panels and spread to the whole car - I have some blistering on the hood of my '78 and it doesn't seem to be spreading.

Don't know if this helps but I thought I'd share it with you any way.

lbell101

I can't see any other way to fix than to refinish down to the depth of the bister. I had a large blister once that I ended up sanding out, spot primeing and blending the repair. Maybe someone else has another suggestion.

Larry

VettePower

Thanks Guys. I'll let you know what my painter says after I stop at his shop after work. :flag

LAvetteman

Was a chemical stripper ever used on the car?

Sharky Guam

Ok, here is a question that I can answer. I paint quite often. Though, I am not a professional automotive painter. I have painted over 300 cars and trucks. Over 100 of them have been corvettes.

Corvettes are very particular on refinishing. The plastic composite bodies on the later models require specialized resins for repair. DIfferent chemicals react quite differently with each other. And only certain paint strippers should be used on fiberglass. The same goes with the type of primer that is used. Even the spot putty can cause problems. On a vette repair, I am very careful on the materials that I use to get the perfect results. My experience is that I only use materials associated with fiberglass repairs when dealing with a vette.

Now to the problem, blistering can be caused by two specific problems. One deals with moisture trapped in the under paint materials. Most primers hold moisture and must be fully dried before painting. Wet sanding just hours before the final coat is sprayed is not advised. I like to put cars in a dehumidified spray booth for atleast 8 hours before applying the paint. My choice though is to use an epoxy primer sealer before the paint is applied. Epoxy primers are superior to the common acrylic lacquer type primers commonly used. The epoxy primer sealer is designed to prevent any moisture from migrating or chemical from cross reacting and causing any deformity in the final product. When doing any type of body work, you must understand that chemicals have to cure. Materials that are two step and utilize hardeners must be allowed to cure before another application is appplied over it. I have found that patience is the key to achieving a perfect repair. Once the repair materials are allowed to cure, you can apply the epoxy or urethane primer sealer combo. Let this cure before doing a light sanding. Some surfacer sealers do not need to be sanded before applying the paint. However, you must let it cure properly. Drying in a spray booth is reccommended. Then before applying the paint, you should tack rag wipe the entire body to remove any dust irregardless of the spray booth conditions.

Moisture trapped in the primer is the number one cause of blisters. They are usually caused by improper drying of the primer after the final wet sanding. Chemical reactions from using uncompatible materials is the number two cause of paint problems. The use of epoxy primer sealers usually eliminates the majority of these problems. That is why it is so widely used.

I hope that this helps others in obtaining the best paint finish on the vette. I have been experimenting with many different materials in dealing with the corvette. As for the paint, any two stage , basecoat/ clearcoat combo, is advised because of its ease to apply and repair. Even an amateur can achieve good results with the modern two stage paints such as DuPont's Chroma Base system. The key to perfection is patience and careful choice of materials.

:)

CF6873

If they are moisture blisters the only cure is to sand to you get to the bottom of them and start over from there. Another thing it could be is solvent popping. In extreme hot weather with certain clears if the surface skins over to soon before some of the solvents are out they can show up as little pimples or blisters. If this is the case many times you can sand the clear and reapply clear and salvage the job. Good Luck, Craig

vetteflame79

Hi
this sounds like orange peel . it is in the glass, comes from heat, happends to most vettes , the only way to get rid of is to samd the glass and remove the orange peel . then seal the area, then repaint :seeya

VettePower

Stopped at the shop on the way home last night. The owner/painter showed me the problem area. It is on the top of the front right fender. This is an area where I used some body glazing putty before I primered with the K36. The painter has guessed that not enough hardner was mixed with the putty, and caused these blisters. He is truly being great about this, as he has offered at no cost to take that entire fender down to bare glass and repair it properly and then repaint it. But first he is going to let it sit acouple of more days in the hot Texas sun to make sure no other blisters come up. As I said before, I only brought it back for touch ups. Before this it had sat in my garage for 3 weeks since I first got it back from him. Being out in the hot sun now is the first time it has really had a chance to start drying. I am keepinig my fingers crossed that no other blisters show up. :nonod:

Paul 75 L82

If the DP40 was shot Ok, I don't think anything under it matrers. It's hard as a rock. Maybe too hard. If the painter let the DP40 set for more than 12 hours it has to get sanded with sotch brite to get the paint to stick. This is very important. lars says to only wait as long as it takes to drink a couple of beers and then shoot on top of the DP. I wouls look at this and mosture in the air lines.

Turbo-Jet

my hood has the 'pimples' as you described. lots of them, but very small (less than 1mm) and are ony visible if you look at a certain angle. it would be nice to know if it just a problem with the clear coat. how can i tell?

VettePower

The pimples sound like air bubbles, which is a whole different animal, and not as bad as blisters. Blisters are bubbles where the paint is actually raised off of the car. :sad:

Darkness

Everybody here is telling good information, but unless you show some pics of the problem it's gonna be dificult to tell. Some have mentioned moister and others orange peel. Can be both, orange peel are tiny little bubbles that look alomost like sand paper and moister are bigger ones and normally are not as much as orange peel.
My .02 :cheers:

VettePower

Lets just say for the hell of it, and I hope I am wrong, that the painter waited more than 12 hours before shooting and did not scuff it up, what are the chances that the rest of the car will blister and peel?

And for Inferno Vette. It is not orange peel. There is no orange peel anywheres on the finish. Rather it looks like a mirror. These are blisters. To descrbe it better,they are like little bubbles of air under the paint. If you slit them with a razor knife you can just peel them back and see what is under it. Something I have not done yet, to see if there is DB40 (red) underneath, or the K36, or the bare glass.

Turbo-Jet

I am going to post pics in a new thread. Please have a look:
http://forums.corvetteforum.com/zerothread?id=349665


[Modified by Turbo-Jet, 3:09 PM 7/24/2002]

Ybnormal

Sorry to hear about you problems but it is good the shop is trying to make it right for you. I looked at the picture but I am not a painter so I have no idea what can cause this. I do like the color of the new paint job and would like to know the specifics of the color number of the paint used etc....it is going to look awesome when you get the it all worked out.

YBNormal...drive a vette

Paul 75 L82

VettePower- you need to talk to Lars! He's the king, if Lars tells you something it's 99.99999999999999 right. If the DP40 sat to long and got real hard you will have problems. I did my paint job different. I sprayied the DP on first and then the K36. My BC/CC is on top of the K36 not on top of the DP. I did a great job in the DP & K36 then hired a painter to do the BC/CC. I have some dimples in my paint, but I'm just going to live with it. But pimples are different. Hope you don't have to sand it all off. Get a hold of lars. Email Grandsport- he's going to see Lars this weekend in Maimi while Lars is on a vacation trip.