Re: Traveller wood refurb question
Posted: Thu Nov 24, 2011 8:53 am
Why's that Neil MGalthough you will still need a cellulose primer on top unless you are a very experienced painter.
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Traveller wood refurb question
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Re: Traveller wood refurb question
Posted: Thu Nov 24, 2011 5:35 pm
The cellulose paint will run straight off! It's almost like painting on glass or bare metal. It is possible by building up thin dry coats, but very difficult to build a nice high gloss coat without getting runs.
30 years ago I worked with a guy who was very good at spraying cellulose on 2k and did it all the time. I have also seen the results from others who tried and failed! So I always used a cellulose primer when spraying cellulose top coat.
30 years ago I worked with a guy who was very good at spraying cellulose on 2k and did it all the time. I have also seen the results from others who tried and failed! So I always used a cellulose primer when spraying cellulose top coat.
Re: Traveller wood refurb question
Posted: Fri Nov 25, 2011 11:55 am
Wow never knew that. Often used 2k primer for a good high build and then cellulosed on top to match the rest of the car. Never noticed a difference myself - far as I could tell, one flatted primer was very much like another...
Must be a better painter than I thought I was!
Must be a better painter than I thought I was!
Re: Traveller wood refurb question
Posted: Fri Nov 25, 2011 4:13 pm
Never had a problem myself either Rubbed down primer be it celly or 2pack should have same grip properties for top coat surely (now someone will come up with the science to disprove me) 
Re: Traveller wood refurb question
Posted: Fri Nov 25, 2011 5:45 pm
OK I'll bite!
The Cellulose primer will absorb the thinners (more and faster) better than the 2k. That means you can put more paint on before it starts to sag. Like if there is a bit of bare metal showing through the primer (cellulose or 2k) that is the place the paint will always sag. This is maybe not an issue for most DIYers as they tend to paint very dry to avoid runs anyway. Very few people seem to be able to put a high even gloss on cellulose. Takes a lot of experience in my view, but I am not a full time painter.
I can feel some test panels coming on!
The Cellulose primer will absorb the thinners (more and faster) better than the 2k. That means you can put more paint on before it starts to sag. Like if there is a bit of bare metal showing through the primer (cellulose or 2k) that is the place the paint will always sag. This is maybe not an issue for most DIYers as they tend to paint very dry to avoid runs anyway. Very few people seem to be able to put a high even gloss on cellulose. Takes a lot of experience in my view, but I am not a full time painter.
I can feel some test panels coming on!
Re: Traveller wood refurb question
Posted: Sat Nov 26, 2011 5:13 pm
OKay
But you should always re prime where you rub through to bare metal. In a booth with two pack we have aerosol primers to spot prime before top coating so i would think it prudent to spot prime bare metal areas on celly finish as it would help to cut down on rust problems in those areas in the future. When applying two pack you always let the first coat flash off before applying second coat and remember the two pack paint is a lot thicker than celly so you would only need two or at the most three coats to get a very high build of paint . But this is all academic as the home sprayer should not be using two pack anyway.
But you should always re prime where you rub through to bare metal. In a booth with two pack we have aerosol primers to spot prime before top coating so i would think it prudent to spot prime bare metal areas on celly finish as it would help to cut down on rust problems in those areas in the future. When applying two pack you always let the first coat flash off before applying second coat and remember the two pack paint is a lot thicker than celly so you would only need two or at the most three coats to get a very high build of paint . But this is all academic as the home sprayer should not be using two pack anyway.
Re: Traveller wood refurb question
Posted: Sat Nov 26, 2011 5:24 pm
Absolutely agree, I was just trying to give an illustration of the effect of primer...
Re: Traveller wood refurb question
Posted: Sat Nov 26, 2011 11:05 pm
That makes sense, the solvents in the cellylose will melt into the solvent based primer more than into the 2k based primer and stick better. Though when I did the painting course' years ago, we were taught to put a light top coat on first and then carry on with heavier coats to get the finish and shine, which is probably why i've never noticed the problem.