Water in paint fail

[JOEPRO]

This went OK the last time when I sprayed a compressor frame. Ronseal water based metal paint. Last time I used about 10% water to make it sprayable. It was still a little too thick but I got away with it and the finish was good.

This time, another compressor frame and same prep inc degreasing etc and it went bad. I did use more water maybe about 20% overall. It sprayed on really nice looked great then about 15 mins later it looked like this



Not drying, reacting in some areas and also running due to not drying etc.

The last day it was in direct sunlight that may have helped. And / or I used too much water.

Question- should I have used water to thin water based paint or was that a mistake? I considered thinners but thought it may have caused chemical reactions on a water based metal paint. Thoughts?

I'll salvage it tomorrow by using a small foam roller to apply a neat undiluted coat of the same metal paint.

 

[Parm]

Quite often the tin will have information on what can be used as thinners

 

[Morrisman]

This went OK the last time when I sprayed a compressor frame. Ronseal water based metal paint. Last time I used about 10% water to make it sprayable. It was still a little too thick but I got away with it and the finish was good.

This time, another compressor frame and same prep inc degreasing etc and it went bad. I did use more water maybe about 20% overall. It sprayed on really nice looked great then about 15 mins later it looked like this

View attachment 416448

Not drying, reacting in some areas and also running due to not drying etc.

The last day it was in direct sunlight that may have helped. And / or I used too much water.

Question- should I have used water to thin water based paint or was that a mistake? I considered thinners but thought it may have caused chemical reactions on a water based metal paint. Thoughts?

I'll salvage it tomorrow by using a small foam roller to apply a neat undiluted coat of the same metal paint.

What else would you use in a water based paint to thin it?

 

[Ross365]

Sounds like a Goldilocks issue; 10% not enough, 20% too much, so somewhere in the middle. Maybe one of those things where there is a very sharp "tipping point"?

 

[Ianb]

What else would you use in a water based paint to thin it?

I am sure I read that at least some 'water' based car paint isnt thinned with water.

 

[steveo3002]

I am sure I read that at least some 'water' based car paint isnt thinned with water.

yes thats right , some horrible smelly stuff last time i used any

 

[tom2207]

has the airline got oil in it ,,, from the compressor ,, the other one often missed is a gun thats been used for hammerite , again maybe not the case here .

 

[JOEPRO]

Update - I brushed on a neat coat of the paint this morning and no contamination showed through and no issues.



I'll put this one down to too much water to make it sprayable. Next time when I'm spraying something like this I'll stick to solvent based paints me thinks.

 

[Parm]

Is that a different colour from the first one ?

 

[JOEPRO]

Is that a different colour from the first one ?

Good question.

This black metal paint comes of the can blue. Then dries black.

So the first shot it was taking hours to dry to stayed blue. Whereas when used neat it dries black much quicker

 

[Parm]

Good question.

This black metal paint comes of the can blue. Then dries black.

So the first shot it was taking hours to dry to stayed blue. Whereas when used neat it dries black much quicker

Maybe the paint chemistry doesn’t like any dilution ?

 

[norsa]

Don't know if it equates but in the olden days I used to heat synthetic paint to reduce viscosity rather than thin it.
Nick