Paint reaction problems continue!!!

[Rubce]

Hi All

Whilst painting the shell at the weekend (Saturday), after applying the second coat of basecoat I noticed there had been a reaction in certain areas. Predominately in the engine bay with a bit more in the gutter by the boot and a few small areas on two wings.

Prior to painting I had washed the shell down, left it an hour rot dry out in the wind and sun and then panel wiped before psuhing it into the garage. I then left it a further hour prior to painting. The paint bubbled up and crazed as happened on the door and bootlid the week before. See http://stagownersclub.mywowbb.com/forum1/4694.html

I had left about 15 minutes between the first and second coat.

Oh bugger I thought. It must still have been damp . So I shut the door and left the paint to dry for three days. On Tuesday evening I wet sanded the affected areas and washed the residue off before drying with disposable wipes.

This evening (24 hours later) I mixed up some 2k primer and hand brushed it onto the affected areas. I then planned to apply stopper tomorrow before smoothing off and reapplying more basecoat at the weekend.

Imagine my horror when the primer started to bubble with 10 minutes of me applying it:shock::shock:

The paint brush was new.

The reaction has taken place along seams, in places no where near seams, on panels which were bare metalled and in the engine bay which still has the old cellulose underneath.

The compressor was not involved in tonights problems.

Prior to this I had sucessfully applied both etching primer and 2k primer to the shell with zero reaction.

What is causing the problem?

Please help.

Bruce (frustrated):shock:

[StagnJag]

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Hi Bruce,

I really feel for you I am sure this wasn't in your game plan:shock:.

Speaking as someone who has absolutely no idea what he is talking about (:?:shock you mention that you used a new brush. Could there have been some residue on the paint brush left by its manufacturing process? I am very wildly guessing silicon or similar to make the bristles look shinier in the shop? A long shot I'm sure.

Just a last random thought before I call it a day.

I am sure one of the more knowledgeable people will be along shortly!

Dave

[Guest]

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Rubce wrote:

Hi All

Whilst painting the shell at the weekend (Saturday), after applying the second coat of basecoat I noticed there had been a reaction in certain areas. Predominately in the engine bay with a bit more in the gutter by the boot and a few small areas on two wings.

Prior to painting I had washed the shell down, left it an hour rot dry out in the wind and sun and then panel wiped before psuhing it into the garage. I then left it a further hour prior to painting. The paint bubbled up and crazed as happened on the door and bootlid the week before. See http://stagownersclub.mywowbb.com/forum1/4694.html

I had left about 15 minutes between the first and second coat.

Oh bugger I thought. It must still have been damp . So I shut the door and left the paint to dry for three days. On Tuesday evening I wet sanded the affected areas and washed the residue off before drying with disposable wipes.

This evening (24 hours later) I mixed up some 2k primer and hand brushed it onto the affected areas. I then planned to apply stopper tomorrow before smoothing off and reapplying more basecoat at the weekend.

Imagine my horror when the primer started to bubble with 10 minutes of me applying it:shock::shock:

The paint brush was new.

The reaction has taken place along seams, in places no where near seams, on panels which were bare metalled and in the engine bay which still has the old cellulose underneath.

The compressor was not involved in tonights problems.

Prior to this I had sucessfully applied both etching primer and 2k primer to the shell with zero reaction.

What is causing the problem?

Please help.

Bruce (frustrated):shock:

I hardly dare say this, but it was suggested some while ago that 2K is a professional medium with several risks attachedand you should stick to cellulose, too late to go back ? Every sympathy mate, but I think you have been misled ! Martin.

[marshman]

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Bruce,

I don't understand why you are getting these problems but I do know how frustrating they are. However, I don't agree that cellulose would have been any better in this respect. As I said in my posts at the start of the threads I have sprayed several cars, the first were in cellulose and the last couple in 2k - I would never go back to cellulose. The "professional" aspect of 2k is down to the isocyanate content and also the slower drying times.

I persoanlly don't think it is silicone - I thnk that is the proverbial red herring. If you had silicone problems you would be seeing the tradmark "fish eyes" all over the place as well.

At this stage I would do the following:

Go back to your paint supplier - show him the pics and get his comments. Whilst there hopefully there will be a steady stream of his regular customers who in my experience are keen to pass on their wisdom. You may pick up a nugget or two of help there.

My other thoughts on the matter are condensation. I think its been hinted at before but your latest eruption occured after applying paint in the evening. I accept that you were spraying in a garage where you have had heaters going etc but can you guarantee that with the doors open as you go in and out there is no risk at all of condensation starting on the panels? One clue might be that all/most of the reaction is on surfaces that a horizontal.

One other comment. I would be a little concerned about the thickness of the paint you are building up. With two pack I was told, this is for the top coats, apply a light "key" coat then one "heavy" coat. I have stuck to this and the paint was plenty thick enough to allow it to be cut back and polished. I will say that I have not sprayed basecoat and laquer other than a single panel I did for a friend a few years back. You also applied the patches by brush, this will be inherently thick.

Might be worth double checking with the paint supplier and on the paint data sheets that any thinners you are using are compatible and also the max amount you can mix in. I know I had two different thinners one for the primer and one for the top coat as well as the gun thinners! The hardnerwas also differnt any chance you have got them mixed up? I know its easy to do as mine all came in anonymous looking white cans.

Hope some of this helps.

Good luck

Roger

[Gresley]

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Hi Bruce,

Sorry to hear of your problems. In my limited experience of spraying paint it is the most frustrating thing ever - I have never got it right!

As Roger says, I wonder if it could be a problem with the paint? I think I would talk to the supplier as he suggests at this stage.

I had a similar reaction on my PI Estate which was entirely my own fault. I stripped the car to bare metal (and there is a lot of it!) and etch primed it. When the sprayer came to wash it off prior to starting to add his primer mine came off in large pieces. Turns out that I didn't realise that you should neutralise paint stripper and I had only washed it off:shock:I had to bare metal the car again. I was not amused!! Another lesson learned!

Brian

[jamcarr2]

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Hi Bruce

You say you washed the shell down before painting . What did you wash it with and where was the car when you did this ?

JOHN

[Rubce]

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Hi John

Before applying the basecoat I washed the shell down with water, dried it and then used Panel Wipe. It was stood on the driveway at the time.

The second time when the primer re-acted, it was washed down with water and then dried, this time whilst in the garage.

I think I might have worked out what went wrong on both occasions.

I think the reaction on the basecoat has taken place because I tried to paint the whole shell in one go. So by the time I had done the engine bay and then got around to the front wings there was an overlap on the painted section with about 5 to 10 minutes between them which is less than the flash off time. In hindsight I think I should have done the engine bay, left it for 15 minutes to flash off and then done the outside. Then repeated the exercise for the second coat.

As regards the problem with the primer bubbling straight away I think I popped to much thinners in the cup whilst making up small quantity of mixture for touching up. I have since re-done the affected areas but with no thinners and it has gone on fine.

Would you agree with my thoughts?

Cheers

Bruce

[jamcarr2]

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HI Bruce

Yes it sounds possible if all goes well with the next coat it sounds like you have cracked it .I wouldn't use water to wash it down between coats though just panel wipe

JOHN

[marshman]

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Hi Bruce,

All sounds feesible. You have to be meticulous when measuring. 2k is much less forgiving on that front than cellulose. I had a plastic measuring jug all marked up with marks at 50% for the paint, 100% for the hardner and 10% for the thinners.

Why did you wash it down each time? When I wet flat I have "clean" cotton rag (old tea towel actually!) that I keep wringing out and when I have fklatted an area I wipe it over with the rag to remove the water and paint that has been rubbed off - I don't actually wash it. Its almost like leathering off a car and the remaining dampness evapourates off very quickly. I then give it a wipe over with panel wipe and just before I start spraying - paint mixed ready to go - I run over with the tac rag.

Hope all goes well in your next session.

Roger

[Rubce]

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Hi Guys

Mixed results this afternoon:?After having rubbed down, reprimed, stoppered and wet sanded the back of the door and the bootlidI then applied basecoat this afternoon. The door has worked a treat and I intend to paint the front side a bit later on.

However, the bootlid has re-acted again in a few places:X. No where near to the same extent as before but re-acted it has. I admit defeat on this panel. There is something on there which the paint does not like. I have wasted enough time on trying to recover the sitaution. So, I now intend to rip all the paint off back to bare metal, apply one coat of etch, filler it, then a coat ofBARCOAT and then high build primer etc. Hopefully that will cure the sod:X:X:X! The underside is laquered so I need to be careful not to mess that side up.

Onwards and upwards

Bruce

[bermondsey]

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hi do you have a water and oil seperater on your compressor ? and try a sealer before primer

[Rubce]

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bermondsey wrote:

hi do you have a water and oil seperater on your compressor ? and try a sealer before primer

Hi Bermondsey

Yes there is a seperator fitted between the compressor and the gun.

As stated I intend to apply a sealer (Barcoat) on the bootlid when I re do it.

Bruce

[kgnich]

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Hi Bruce,

Sorry to hear of your frustrations. I've been there too. I have found that panel wipe doesn't always remove all contamination. I don't know whether this will be frowned upon by the paint pros but I now use sugar soap to wash everything down. This seems a lot more powerful than panel wipe. I still use panel wipe/tac wipesprior to painting but since using sugar soap have never had a reaction .... all with two pack.

Might this help??

Cheers

Graham