old paint lifting during respray

[flashman1207]

Damn damn damn. Just finished fixing up the gutters and roof line of the GQ but had a small spot on the roof that needed sanding back and painting. Well, the old paint is just crap, thin and just comes away with a scrape of the finger. So sanding and feathering is impossible. I would just spray it but problem is that the old paint just lifts away around the edge when I spray primer or new paint on it. Its obviously been resprayed in the past and the paint did not stick well at all so any new paint is going under it and lifting it. Causes like a jagged raised edge. Looks shit. I kept sanding back looking for some decent old paint but the hole is now about 200mm x 200mm and there is no sign of the crap paint stopping. Can't afford a full respray (specially as I just fixes up the gutters and roof edge so well). Anyone got any idea how I can stop the old paint lifting ?

Thx
Flash

[Parksy]

Doesn't sound like you're going to have much luck unless you remove all the old crap first. Unless you remove the old stuff, you're only going to have issues down the track.

[MudRunnerTD]

Hey Flash,

my whole roof paint came away in sheets mate! had to get the whole roof.

I am no paint expert mate. pm Alitis007 he knows a fair bit about it.

I would recommend maybe swapping to acrylic just for the roof mate, it should not lift the old paint. It will be the Thinner in your new paint reacting to the old paint and lifting it! you will be there for ever! it acts like paint stripper bleeding under the edge.

[Alitis007]

Sorry to say but you need to take the roof back to bare metal mate, nothing you put on it will stick. The problem is the original base coat was not applied correctly hence why its reacting with the newpaint. Paint stripper is your friend for this but wear glove and eye protection because it is acid and help it react with a heat gun, but not too hot coz you will make it harden up again. You will still need to sand it with 400 grit ( on an orbital is you have one) then etch primer and hi fill ( undercoat). The hifill will also need to be sanded down with 240, 400 then 800 then apply paint.

Acrylic is easy to paint at home but it absorbs water so eventually you roof will rust.

If you can get your hands on a spray gun and a compressor you could do it your self or if you know a spray painter they will know the ratio to mix the paint like hifill ( some) 3:1:1, solid paint ( eg white, red etc) 2:1:1, metallic 3:1:1 0r 4:1:1 depending how warm your climate is.

[Alitis007]

I should also mention how many coats to apply
Etch primer 1 haze coat, 1 cover coat no sanding needed
Hifill 1 haze, 1 cover 1 or 2 final coats, guid coat ( use a can of pressure pack enamel ) after you sand with the 240 spray another guid coat and do the same after the 400
Paint 1 haze, 1 cover , 1 final coat

You can also drive around in hifill and paint afterwards. I drove my old vl in hifill and guid coat for 6 months.

[Parksy]

That's interesting about how acrylic absorbs water. Is that because of the way it dries, by leaving microscopic holes when the vapours evaporate?
Is this problem inevitable?

[flashman1207]

Hey Flash,

I would recommend maybe swapping to acrylic just for the roof mate, it should not lift the old paint. It will be the Thinner in your new paint reacting to the old paint and lifting it! you will be there for ever! it acts like paint stripper bleeding under the edge.

I'm actually using Holts spray cans which are Acrylic I think. So should I try something else (enamel perhaps?). For the best result yes I should redo the whole roof but I just don't have the time or money. I think the etch primer i was using was Epoxy.



If you can get your hands on a spray gun and a compressor you could do it your self or if you know a spray painter they will know the ratio to mix the paint like hifill ( some) 3:1:1, solid paint ( eg white, red etc) 2:1:1, metallic 3:1:1 0r 4:1:1 depending how warm your climate is.


Thats a possibility, never done it before though. If I can't come up with an interim solution then might have to go down this route. I have access to a compressor...

Thanks for all the responses guys... appreciate it

[Alitis007]

That's interesting about how acrylic absorbs water. Is that because of the way it dries, by leaving microscopic holes when the vapours evaporate?
Is this problem inevitable?
Look to be honest my knowledge is limited to what i have asked my relos who are panel beaters and spray painters, i do my own panel beating and panel repairs and usually get them prepped for painting to have my cars painted by my cousin but i try and paint odds and ends so i can master the skill of using a spray gun.

What i do know is when Acrylic paint is being made there is a small water content when it is being made. During application it absorbs moisture from the air, while curing the water in the paint from being made and the water it has absorbed from the air evaporate leaving the microscopic holes that you speak of allowing the water to seep underneath it when the car has sat for a prolonged period of time.

Acrylic paint always has a better orange peel than 2pac enamel in the hands of an amateur but the fact that the 2pac has a higher solvent base with no water in the making process it doesn't allow moisture to affect the steel as much, even tho Acrylic is stronger then 2pac once it has cured.

This is the last thing i painted, rear valance ( beaver panel )
31200
Bonnet
31201
I still need to paint 2 doors and a guard for my brother, wish me luck lol :)

[Alitis007]

I'm actually using Holts spray cans which are Acrylic I think. So should I try something else (enamel perhaps?). For the best result yes I should redo the whole roof but I just don't have the time or money. I think the etch primer i was using was Epoxy.



Thats a possibility, never done it before though. If I can't come up with an interim solution then might have to go down this route. I have access to a compressor...

Thanks for all the responses guys... appreciate it

Theres your problem right there, Acrylic paint on 2pac enamel, big no no. As you would have found out the edges would have wrinkled up first then bubbled the rest. You can get pressure pack cans of 2pac color matched for around $40 a can from a reputable automotive paint supplier but thats a bit expensive, for the time being i say rub it back and leave it in hifill till you can affort to paint it. IMO thats the best way coz you will have sealed the steel from the elements and are half way to the painting process.

[flashman1207]

Thanks Alitis007. So I need to get an Epoxy hifill as well then (by hifill do you mean primer filler?) as my current primer says epoxy on it....

[Alitis007]

Thanks Alitis007. So I need to get an Epoxy hifill as well then (by hifill do you mean primer filler?) as my current primer says epoxy on it....

Sorry for the late reply mate, but yes Hifill is primer filler. I'll have a look at what i have when i go back to work and i'll tell you what it says on the container, when i go to the paint shop i just ask for 2pac ( i think it may be epoxy but i'll let you know) you will also need hardener and 2pac thinners, a few mixing sticks and mixing cups with the ratios and measurements on the side, like this
31320

But like i said i'll get back to you when i suss out what i have....

[gu8 patrol]

you can put acrylic paint on 2 pac you just need to apply isolator first which will eliminate any flashing or peeling.

[04OFF]

Not sure about a Acrylic paint job absorbing water causing good panels to rust ?, a good Acrylic paint job should last years in the weather without causing rust.

This is my torrie, this Acrylic paint job was about 10 years old at the time of the video, it sat out in the weather heaps, hardly ever got polished, and red is the worst colour to have outside.....


https://www.youtube.com/watch?v=HBZycNtX9zY



Now just Acrylic "primer" WILL definaitly absorb moisture, and this is why you should NOT drive a car around in primer as a lot of people do (some 2pac primer is OK)







even tho Acrylic is stronger then 2pac once it has cured.


I think you mean the other way around ? (2pac is way stronger than Acrylic.)







you can put acrylic paint on 2 pac you just need to apply isolator first which will eliminate any flashing or peeling.


Agree, Acrylic over 2pac is no problem, "if", your Acrylic paint is old enough (so has done all the moving around and bleeding of thinners it will do ,this can take years) you can get away with painting 2pac over it.

[flashman1207]

OK guys, job finished. Got some Isolator, jeez wish I knew about this stuff before I started, would have saved me days of work. Anyways, as I said before, wasn't able to feather the paint as it just kept coming away so sanding back as much as I could, then 3 coats of isolator, sanding back the 'high' side after each coat. 3 coats of primer (sand again). 4 or 5 coats of top coat. Looks pretty good. You can still wear it wasn't fully sanded back in places but by the time i've cut in and polished it I don't think you would notice. Its not a show car and spends most of its life grimey so not fussed......

Thanks to all

PS I 'cut' the rest of the car as well. Jesus, what a difference. Looks brand new..... well.... sorta

[mick.]

Damn damn damn. Just finished fixing up the gutters and roof line of the GQ but had a small spot on the roof that needed sanding back and painting. Well, the old paint is just crap, thin and just comes away with a scrape of the finger. So sanding and feathering is impossible. I would just spray it but problem is that the old paint just lifts away around the edge when I spray primer or new paint on it. Its obviously been resprayed in the past and the paint did not stick well at all so any new paint is going under it and lifting it. Causes like a jagged raised edge. Looks shit. I kept sanding back looking for some decent old paint but the hole is now about 200mm x 200mm and there is no sign of the crap paint stopping. Can't afford a full respray (specially as I just fixes up the gutters and roof edge so well). Anyone got any idea how I can stop the old paint lifting ?

Thx
FlashBy the sounds of it you didn't want to spend a lot of money. I'll put this up for future reference for anyone wanting to dodge up some flaky paint. lol

If you want to do it properly then paint striping, etching and a 2 pack primer is your best bet prior to repainting as mentioned above. However if you don't want to strip the roof back to bare metal and can get it feathered out a little bit you can use a 2 pack sealer such as PPGs Scan sealer (similar to the isolator your referring to) which will hold down any lifting paint around the edges. Now this is not a total cure but if you just want to hold the edges down this will do it. I've used this on heaps of old bombs that people just wanted one colour all over for rego or to sell off with a cheap respray.

Just to clear a couple of things up both acrylic and 2 pack primers, hyfills, spray polyesters etc are all porous meaning they all absorb water it's just some such as acrylic and polyesters absorb it quicker then 2 pack primers.

Only top coats work like a sealer and don't absorb water and this goes for acrylic and 2 pack.

I would personally paint strip the roof and do it properly but yes it can be dodged up with a scan sealer if you don't want to go all the way.

Alitis007 who told you there is water in acrylic paint which makes it porous? I was an automotive Technical paint rep before I got out of the game and I know the ins and out of paint pretty well and that's a new one on me. lol All primers are pretty much porous but the only ones that have water content and it's very very small is waterbourne primers and bases. I'm not saying it's not totally true but I would have thought in all the training I've done over the years I would have heard this somewhere myself by now.

You can also put acrylic over 2 pack enamel but you cant put (not supposed) to put 2 pack over acrylic but you can. lol Air dry enamel will go over anything.

In fact a lot of old school painters will use a 2 pack primer and then respray with acrylic. I personally wouldn't but it's done pretty often.

Cheers Mick

[Alitis007]

By the sounds of it you didn't want to spend a lot of money. I'll put this up for future reference for anyone wanting to dodge up some flaky paint. lol

If you want to do it properly then paint striping, etching and a 2 pack primer is your best bet prior to repainting as mentioned above. However if you don't want to strip the roof back to bare metal and can get it feathered out a little bit you can use a 2 pack sealer such as PPGs Scan sealer (similar to the isolator your referring to) which will hold down any lifting paint around the edges. Now this is not a total cure but if you just want to hold the edges down this will do it. I've used this on heaps of old bombs that people just wanted one colour all over for rego or to sell off with a cheap respray.

Just to clear a couple of things up both acrylic and 2 pack primers, hyfills, spray polyesters etc are all porous meaning they all absorb water it's just some such as acrylic and polyesters absorb it quicker then 2 pack primers.

Only top coats work like a sealer and don't absorb water and this goes for acrylic and 2 pack.

I would personally paint strip the roof and do it properly but yes it can be dodged up with a scan sealer if you don't want to go all the way.

Alitis007 who told you there is water in acrylic paint which makes it porous? I was an automotive Technical paint rep before I got out of the game and I know the ins and out of paint pretty well and that's a new one on me. lol All primers are pretty much porous but the only ones that have water content and it's very very small is waterbourne primers and bases. I'm not saying it's not totally true but I would have thought in all the training I've done over the years I would have heard this somewhere myself by now.

You can also put acrylic over 2 pack enamel but you cant put (not supposed) to put 2 pack over acrylic but you can. lol Air dry enamel will go over anything.

In fact a lot of old school painters will use a 2 pack primer and then respray with acrylic. I personally wouldn't but it's done pretty often.

Cheers Mick

What i was told about Acrylic paint was from an old panel beater that my dad used to know but come to think about it he might have been an unreliable source TBH, he called himself the panel king hahaha but he used to cut out rust and replace it with news paper and chicken wire with a skim of fibre glass and bog........

Happy to be corrected about acrylic coz i only play with 2k refinishers.

[mick.]

I've been using 2 packs for years in medium solid, high solid and Ultra High Solid plus most water based products on the market but I've had very little to do with acrylic. I'd say there are a lot of back yarders on here that have more experience then me with it. I don't thinks its correct though as I'm sure at some stage with the amount of crap they teach you as an apprentice at Tafe and the training I had to be a Technical paint rep they would have mentioned this. The reason being as most of the stuff they teach at Tafe is useless in the real world so that's where you would here it. lol

Most of the useful info is taught by good tradesmen more then anything. The guy you mentioned above doesn't sound like someone I would hire. lol

Cheers Mick

[Alitis007]

I've been using 2 packs for years in medium solid, high solid and Ultra High Solid plus most water based products on the market but I've had very little to do with acrylic. I'd say there are a lot of back yarders on here that have more experience then me with it. I don't thinks its correct though as I'm sure at some stage with the amount of crap they teach you as an apprentice at Tafe and the training I had to be a Technical paint rep they would have mentioned this. The reason being as most of the stuff they teach at Tafe is useless in the real world so that's where you would here it. lol

Most of the useful info is taught by good tradesmen more then anything. The guy you mentioned above doesn't sound like someone I would hire. lol

Cheers Mick

Alot of backyarders do use acrylic so they get a better orange peel without having to use an oven. At the time i was told about the water in acrylic it made sense coz of the cars i had seen with water marks that couldn't be removed with polish and most of the cars had crows feet.

I agree trade school is bollocks, its only good for talking trash and the week holiday every 6 weeks lol. Saying that, i am a qualified mechanic but i did my 4 year apprenticeship in a year and a half, 300hrs ahead of the proposed schedule and 6 of those months i did nothing but play cards lol untill they threatened to make me re do all my modules hahaha!

Don't worry about that bloke mate, he's locked up now for assaulting a would be thief that he caught trying to break into his car, which he beat within an inch of his life lol ( not funny, i know but you have to laugh )

I now get my info about 2k from my cousin who is a sort after spray painter around my area who tells me how, what and why i need to do things to get the correct result!

[flashman1207]

By the sounds of it you didn't want to spend a lot of money. I'll put this up for future reference for anyone wanting to dodge up some flaky paint. lol


Cheers Mick

Right there Mick, I wanna fit a turbo and am just about to go on hols so money is tight..... Not too mention the bigger tyres etc I want. And the wife wants a new car... etc etc etc

Anyways, the job has come up good... bloody good actually. I will update the thread with how the paint holds out. Would it be worth putting a clear coat on? If so, should I cut it back first or wet and dry before spraying?

If I could just keep the roof rack off I'm sure it would last better..... Got one of them Oztents though, don't fit inside the truck

[mick.]

If it's a solid colour such as white I wouldn't really bother if your trying to keep the costs now and the wife happy. lol

Cheers Mick