primer question

Belgian1979vette

Belgian1979vette

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Apr 4, 2008
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Location
Koersel/Belgium
I have already shot several layers of primer each sanded in between. The result is looking pretty good even when making it wet. However I keep having some little spots where I sand through the last layer. In principle they are high spots.

Should I keep on putting on primer and sanding till there are no spots where I sand through.
 
You're using a long sanding block ? Then yes, these are high spots. How many coats of primer did you spray ? Is this high build primer ??
I'd keep sanding the high spots down and then spray one more coat primer.
 
I'm block sanding it. The block is not that long, about 10 cm long, since I didn't find a longer block suited for the grit paper i'm using. Thing is that these cars are so curved that a longer block won't do much good. I'm sanding in a cross patern. I gues I'll be doing one more coat.

Untill now she had 2 coats of epoxy type primer and about 4 normal of the normal type. I don't spray it thick..

Anyway she looks very good, but it's difficult to asses without any shining paint on it, and the water only just gives an idea.
 
Is the epoxy primer a different color ? If so I'd sand the high spots some more, stop when you get down to the epoxy.
 
Don't you have A4 sheets of sandpaper ? You should be able to use a 10" long block (250mm).... at least.... 600 grit comes in 8.5X11 sheets here in the US, close to DIN A4 format.... or do you use the paper on a roll ??

When I use my 11" block it really shows low spots a lot better than a shorter block.
 
MYBAD79 said:
Don't you have A4 sheets of sandpaper ? You should be able to use a 10" long block (250mm).... at least.... 600 grit comes in 8.5X11 sheets here in the US, close to DIN A4 format.... or do you use the paper on a roll ??

When I use my 11" block it really shows low spots a lot better than a shorter block.
Click to expand...

Well we do have that A4 sheet, but the 10" block I had, just had to much foam under it and that foam was doing funny things when using water with it. It kept wrinkling the paper (if that is what it is called in English) and I could get the paper to stay on that block with the foam soaked... Anyway the foam was a little to soft in my opinion to get it smooth enough. Then I found this 10 cm long block with just a very thin layer of foam under it. It straightened out much of the high spots and it kinda looks like glass when putting on water to see if there are any high spots.
Anyway the number of sand through spots are getting smaller and I'm not sanding as deep into the primer anymore to get all the sanding key (black) off. Right now, I'm only sanding through the last layer of primer in some spots. Guess I'll be putting on this last layer :huh2:
 
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cajos1968 said:
First filler, then primer. In between lots of sanding!!!!
Click to expand...

Well i'm long past the filler thing.

Some suggested using a sprayable filler, but my paint shop advised against it, because it could shrink. They suggested building it up with primer and sanding in between layers. Never thought I would need that many layers however.:suspicious: Maybe that was just a salestalk to get me to buy lots of primer.
 
you're spraying it 'thin' - I assume with a little reducer in the primer ?? 3-4 coats of high build primer without reducer are not too much IMO, especially if you sand most of it off between the coats....

why not simply find yourself a nice straight 12" piece of wood (like a 2x4 or 8x10cm) ?? Before they started selling these fancy foam sanding blocks that's what people used... LOL ....

don't forget to post some photos of the progress :thumbs:
 
MYBAD79 said:
you're spraying it 'thin' - I assume with a little reducer in the primer ?? 3-4 coats of high build primer without reducer are not too much IMO, especially if you sand most of it off between the coats....

why not simply find yourself a nice straight 12" piece of wood (like a 2x4 or 8x10cm) ?? Before they started selling these fancy foam sanding blocks that's what people used... LOL ....

don't forget to post some photos of the progress :thumbs:
Click to expand...

And paint sticks which I still use...
LOL.

Danny
 
cajos1968 said:
Primer is to prime the surface for paint. Filler is to fill up. I think it is rather strange advice from the paint shop.

http://www.icc-forum.nl/invision/index.php?showtopic=235

If you speak Dutch I can bring you into contact with my painter for some secondary advice?
Click to expand...

I'm pretty sure his body work is done and now he is spraying high build primer to block it flat and yes if he is sanding it off, than perhaps his low spot need to be glazed but without pictures it hard to tell what someone is doing wrong.

Danny
 
His shop advised him to build up with primer. I'm not sure that will work if the difference is to big. With primer you can only "fill" minor deviations. Even a professional painter will have problems with bigger highs and lows.

My painter lives in Eindhoven, that's 30 minute drive or so from Koersel
 
Ok, here goes :

IMG_0981.jpg

IMG_0984.jpg

IMG_0986.jpg
 
Is it necessary to sand between primer coats? I was told to put two coats of epoxy primer and start blocking. He also said it was ok to put some hig build primer after the epoxy and then start sanding. Is that right?
 
It depends on the manufacturer, the epoxy that I used needed to cure overnight before applying high build primer.
I would not want to block epoxy - it's not as sandable as regular high build primer like shopline urethane. Actually I think epoxy is terrible to sand or block.

Most epoxy primers do not require sanding if the topcoat is applied within a few days. After a week the epoxy needs to be sanded and another coat of epoxy applied - at least that's what the two brands that I used required....

Personally I like a darker (black) epoxy primer and grey urethane primer. The high spots will be very visible, if the black epoxy is exposed in a few spots stop sanding and apply more primer....
 
I did get the black epoxy just for that reason. I agree with you on sanding epoxy, I will be priming over it then with grey primer. What grit do you block the primer at?
 
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