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Author Topic: Car spraying  (Read 239 times)

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Kieran

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Car spraying
« on: 11 May 2019, 15:26:34 »

Hello all

I was just hoping to get some advice. Been repainting the roof of my Senator and all has gone really well. Will be laying down the laquer tomorrow after going over it with wet and dry. What I need to know before I start is do you need to thin out the laquer like you do with basecoat. The current ratio for basecoat is 2 to 1.

Thanks
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Nick W

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Re: Car spraying
« Reply #1 on: 11 May 2019, 15:55:48 »

If you're using 2-pack lacquer, then you mix the paint and activator to the manufacturer's ratio. Then you add thinner as necessary so that it sprays well; less in hot temperatures, more in cold. That's rarely more than about 10% extra.


Why are you going to sand the basecoat? If the finish and colour are even, that's all you want. The shine and smooth finish are provided by the lacquer.
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Kieran

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Re: Car spraying
« Reply #2 on: 11 May 2019, 16:34:07 »

Hello

It's not two pack. Lightly sanding the basecoat to remove the small nibs from spraying. Using 2500 grit so it's not much. All my knowledge of spraying has come from You tube Harrison painting guide. So far it's gone  well. So because it's not two pack do I not need to thin it.

Thanks
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Nick W

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Re: Car spraying
« Reply #3 on: 11 May 2019, 16:39:20 »

Hello

It's not two pack. Lightly sanding the basecoat to remove the small nibs from spraying. Using 2500 grit so it's not much. All my knowledge of spraying has come from You tube Harrison painting guide. So far it's gone  well. So because it's not two pack do I not need to thin it.

Thanks




Basecoat is very thin, and I would be very surprised if you don't end up with very visible scratches under the clear.


If the clear is not 2 pack then you'll definitely need to thin it!


I there a label on the tin, as that should tell you. You really should have got the data sheet when you bought the paint
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Kieran

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Re: Car spraying
« Reply #4 on: 11 May 2019, 18:01:43 »

Well maybe I should have got the data sheet but none was offered and I wasn't to know. Anyway back to sanding between base and clear. Done alot of research into this and none the wiser. So many conflicting tips on sanding and not to. Some people swear that it gives s much better finish and helps the laquer to bond. Others say it will ruin the finish and has to be applied soon after basecoat. Mine has now been drying for 2hours. Confused.
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razzo

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Re: Car spraying
« Reply #5 on: 11 May 2019, 18:46:38 »

Usually base coat does not need to be sanded unless faults are showing, I would be inclined to clear coat over base soon as itís flashed, 2 pack clear is far more hard wearing than cellulose and much easier to work with. Leaving car for any length of time before lacquer will just result in higher possibility of surface attracting airborne crap, but yes I would thin clear coat
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Nick W

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Re: Car spraying
« Reply #6 on: 11 May 2019, 19:58:27 »

Well maybe I should have got the data sheet but none was offered and I wasn't to know. Anyway back to sanding between base and clear. Done alot of research into this and none the wiser. So many conflicting tips on sanding and not to. Some people swear that it gives s much better finish and helps the laquer to bond. Others say it will ruin the finish and has to be applied soon after basecoat. Mine has now been drying for 2hours. Confused.


The data sheet gives you all of this info. I wouldn't sand a basecoat unless it had lots of runs or dirt in it. And even then, I'd probably apply another coat.


The lacquer doesn't form a mechanical bond with the basecoat, but a chemical one. So sanding doesn't help. That's why you need to apply it within a certain window, so that the various layers crosslink. This is usually done once the base has flashed off or at least within a couple of hours, but the data sheet will tell you the maximum -the Lechler Acrifan I use(2pack though) suggests within 24hours
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Kieran

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Re: Car spraying
« Reply #7 on: 11 May 2019, 20:14:11 »

Decided against sanding. The window for lacquer for the paint I am using is 24 hours. So hopefully another nice day tomorrow I will laquer the car. Pictures to come soon.
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Keith ABS

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Re: Car spraying
« Reply #8 on: 12 May 2019, 07:01:02 »

 To throw another spaner into the works, when I was reguarly using ICI autocolour single pack basecoat and laquer, the laquer was used straight from the can, no thinning
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Nick W

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Re: Car spraying
« Reply #9 on: 12 May 2019, 07:52:49 »

Then there's water based, which uses 'thick' water.


Which is why the data sheet is necessary for a proper answer.
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Keith ABS

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Re: Car spraying
« Reply #10 on: 12 May 2019, 20:43:33 »

 The basecoat is water based.
The laquer is still 2 pack as it needs the resistance to moisture from its chemical cure
Unless technology has moved on in the last four years since I was last in a body shop
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