Do I need primer?

[andyv]

I've been spraying cellulose on the top half of my VW camper. Most of the old paint has been in good condition, but I've dealt with some rust which is mostly hidden by the window seals. I sanded it down and gave it all a coat of grey primer then white on top and it's worked OK.

For the future however, if I'm spraying on top of old paint and not changing the colour is it essential to put primer on? Apart from areas being repaired can I just sand it and put on top coat?

 

[superfly]

I am not an expert at all, but I would always prime, so you are restarting with a fresh stuff.
I would also use etch prime, if you sand a lot to remove rust from now on.

I did a repair on my van few year ago and I have to do it all ago, the primer was not good neither the paint.

But I would that it does not mean you van will have the same problem, I think it is a matter of trying and failing, eventually you are getting right :-)

 

[norsa]

If the paint is sound then you only need spot prime the repairs and key up the original. However. If you have lots of little spot repairs on a panel, you had just as well prime it all.
Nick

 

[langy]

If the paint is sound then you only need spot prime the repairs and key up the original. However. If you have lots of little spot repairs on a panel, you had just as well prime it all.
Nick

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