Spraying 1k over 2k primer

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PostPosted: Tue Dec 02, 2014 4:32 am
Lba wrote:Thanks for that response.

2k is 2 pack paint and 1k is acrylic in Australia.

Thanks


1k and acrylic are different, im not sure of the chemical make up differences, however I know that 1k and acrylic primers are different, I would imagine the paints will follow suit!!

however, you shouldn't have any probs with going over 2k primer with 1k, you cant go 2k or 2pak over acrylic as you will get solvent pops, but you can go 2k or 2pak over 1k as most etch and plastic primers are 1k and are suitable for 2k or 2pak paints.
krem

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PostPosted: Tue Dec 02, 2014 8:44 pm
krem wrote:1k and acrylic are different, im not sure of the chemical make up differences, however I know that 1k and acrylic primers are different, I would imagine the paints will follow suit!!


1K means that the paint is a single component, air dry. So it does not have any hardener in it and dries by evaporation of the thinners used to carry it to the panel. What we refer to as acrylic here is all 1K but there are other 1K paints as well, enamels, for example.

krem wrote:you cant go 2k or 2pak over acrylic as you will get solvent pops, .


Untrue. As with any paint, the primer must be dry before overcoating. 1K acrylic automotive paints are 100% compatible with paints from a 2K system with only a very few exceptions like iso-free primers and clears. What neither are compatible with is enamels and other paints not intended for automotive use.

For example, I did a couple of panels on an MG-B recently. There was some minor rust to be repaired and I then used an epoxy primer for protection followed by a 2K urethane primer and then the acrylic topcoats to provide a 'period correct' finish that matched the rest of the car.

I often use 1K primer as a sealer/surfacer for small repairs or where there is still a cover over the metal.
Chris



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PostPosted: Wed Dec 10, 2014 4:48 am
I have always been told that the thinners from acrylic take yrs to fully evapourate, and if you for example put a 2k clear over an acrylic base, the solvents cant evapourate thru the cured clear and will eventually "pop" thru the clear to get out,
krem



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PostPosted: Sun Dec 14, 2014 6:36 am
Thanks for all the information it has been valuable

I've convinced the panel beater to cover his work in protec acrylic primer so I can use acrylic paint (protec) straight over it . He claims all his work in the past have had a 2 pac primer but after speaking to the protec rep he was happy to use the acrylic primer as I asked. I guess the rep must have said something worth while

Cheers everyone



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PostPosted: Sun Dec 14, 2014 6:41 am
krem wrote:
Lba wrote:Thanks for that response.

2k is 2 pack paint and 1k is acrylic in Australia.

Thanks


1k and acrylic are different, im not sure of the chemical make up differences, however I know that 1k and acrylic primers are different, I would imagine the paints will follow suit!!

however, you shouldn't have any probs with going over 2k primer with 1k, you cant go 2k or 2pak over acrylic as you will get solvent pops, but you can go 2k or 2pak over 1k as most etch and plastic primers are 1k and are suitable for 2k or 2pak paints.
krem



My understanding was that 2k and 2pak are the same name in Australia. Both systems use a hardner, where as acrylic is a 1k or single pac - although I have never heard of it being called 1k here, as acrylic is one stage without hardner I have been told it's a 1pak-1k here

Im probably wrong and krem I stand corrected. Thanks

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PostPosted: Sun Dec 14, 2014 9:12 pm
Not quite. 2K is generally used to mean an activated solid colour. It comes from the 2K brand by PPG that used to stand alongside Cobra which was for Clear Over Base.

2 pack is a generalisation to mean any paint that has a hardener in it. Could be primer, a solid topcoat or clear. They're all 2 pack paints because the have two components that come in two different PACKages.

1K is usually referred to as acrylic, but sometimes 1K, especially when talking about primers. It's the same chemical composition, acrylic. The only exception is enamel, which is called, strangely enough, enamel, not 1K (even though it is).

Acrylic can be overcoated with a 2K clear after flash, usually about an hour.

I rather feel that this whole issue is somewhat moot. If the beater primes in a 2K primer then all you have to do is block back and apply your topcoats. There is no need for another layer of primer unless it's to take out variations in the panel.
Chris
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