My basecoat came out blotchy, I'm wet sanding the basecoat with 600 - at what point would it require applying more primer? Just not sanding past the primer the base was laid on top of?

Just don't want to wet sand to 600 and find out later that I needed to reprime before appying base coat again. Are burn throughs in the base coat acceptable as long as it doesn't go past the primer?

What is it with you guys and P600? Are you going to reprime it? Or do you just want to see the sanding scratches when you've finished?

If not, P800 is the correct grade.

A few small rubthroughs will be fine.

What is your plan to ensure that, when you redo it, it doesn't come out blotchy again?

NFT5 wrote:What is it with you guys and P600? Are you going to reprime it? Or do you just want to see the sanding scratches when you've finished?

If not, P800 is the correct grade.

A few small rubthroughs will be fine.

What is your plan to ensure that, when you redo it, it doesn't come out blotchy again?

TDS calls for 500 grit, figured 600 was acceptable.

As far as the blotchyness I will make sure I do 75% overlap like the TDS calls for... and spray on a test panel first. Open for any other suggestions you have.

Would you care to let us see this TDS? Link to online or a picture uploaded here.

I have seen P500 specified but only dry and only if done by machine, DA or similar. I'm interested to know what base would specify such a treatment, and why.

75% overlap is also a bit unusual. Don't think I've done a 75% overlap, ever, in my life. Go a bit slow or have the fluid turned up and that would be running off the panel like Niagara Falls.

NFT5 wrote:Would you care to let us see this TDS? Link to online or a picture uploaded here.

I have seen P500 specified but only dry and only if done by machine, DA or similar. I'm interested to know what base would specify such a treatment, and why.

75% overlap is also a bit unusual. Don't think I've done a 75% overlap, ever, in my life. Go a bit slow or have the fluid turned up and that would be running off the panel like Niagara Falls.

Sure thing, its restoration shop brand paint.. took a screenshot and underlined what I read from it

That brand isn't sold here but I do see what they're doing. To comply with the onerous (ridiculous?) VOC regulations they use a lot less thinner so that less evaporates and they can comply. But, the 75% overlap says to me that the paint has pretty ordinary coverage.

I've seen P600 sanding scratches in paints that aren't high solids so I'd recommend against using that grade, especially wet. P800 is much safer and will not compromise adhesion one bit.

Curios your thoughts, maybe it will help the OP. Not sure why he thinks more primer. I would say just another coat of base if anything.

My primer was sanded to 320. 3 coats of base. I tried my hand at some de nibbing and spot sprayed those areas. I didn't have faith that those blends would not be visible under the clear, so I scuffed the whole roof with maroon scotchbright. Then I sprayed a 4th coat of base.

I probably should have sanded finer, especially since the tds specified 400 machine or 500 wet. But I was tired of burning through all the ridges.

Point being. The 600 isn't the end of the world.

acro wrote:Curios your thoughts, maybe it will help the OP. Not sure why he thinks more primer. I would say just another coat of base if anything.

My primer was sanded to 320. 3 coats of base. I tried my hand at some de nibbing and spot sprayed those areas. I didn't have faith that those blends would not be visible under the clear, so I scuffed the whole roof with maroon scotchbright. Then I sprayed a 4th coat of base.

I probably should have sanded finer, especially since the tds specified 400 machine or 500 wet. But I was tired of burning through all the ridges.

Point being. The 600 isn't the end of the world.

Not necessarily saying I need more primer. I would like to know - at what point would I have to apply more primer? Wasn't sure if wet-sanding the previously applied basecoat to 600 is sufficient enough even with burn throughs to the primer coat. TDS just says if allowed to sit for over 24 hours then scuff and apply more base... I've got to correct a blotchy job so I'm wet sanding 600 and possibly 800 but it is cutting through to the primer in some areas.

I would be extremely happy if I can get my paint job to look as nice as that..

NFT5 wrote:That brand isn't sold here but I do see what they're doing. To comply with the onerous (ridiculous?) VOC regulations they use a lot less thinner so that less evaporates and they can comply. But, the 75% overlap says to me that the paint has pretty ordinary coverage.

I've seen P600 sanding scratches in paints that aren't high solids so I'd recommend against using that grade, especially wet. P800 is much safer and will not compromise adhesion one bit.

Thanks - guess I'll get me some 800 as well. So, no primer or sealer should be needed on top of this 800 wet sanding of the base (which was applied on top of wet sanded 600 primer) with areas that are burn-thru to the primer