[roger1]

Originally Posted by baddbob

Another thing that's got me curious is the 400 grit starting point for the colorsanding, I've used 600 and 800 but 400 sounds a little rough? I don't mean to be a nosey PITA just trying to pick up a few tips and get your opinions . Here's to more good days Bob

I've been kind of scratching my head on this also. I tried this once with SS urethane and couldn't get the 400 scratches out with 1000.

[rrmccabe]

I suppose I should know this, but what is the difference between Orange Peel and Urethane peel ?

I notice a lot of Urethane cars that have a material ripple in them and look like the topcoat should be blocked. I was always guessing someone sprayed, sanded and buffed before it totally cured.

So.. what is it?

Rich

[baddbob]

Orange peel is caused from poor application, urethane peel is inherent to urethane paints and IMO can't be completely prevented. Sometimes it's worse than others and I think percentage of solids has a major influence. I've seen some pretty perfect as sprayed finishes, slick, wet and smooth but they always have some amount of urethane peel. Cutting them out with a block is your only way to remove them. I know some people seem not to notice it at all and others seem to just ignore the fact that they are there, but when they are gone you end up with that nice flat straight finish similar to the old Nitrocellulose Lacquer days. The older medium solid urethanes seemed to be less prone to urethane peel IMO. Maybe it's a result of texture stack up. ??? Bob

[beemdubya]

Yea. urethane wave is what my old shop teacher used to call it.. im still trying to figure out how those 400 scratches are gonna come out.. but i guess if u sand one panel with 1000 after 400 for quite a while it should come out at some point..

[rrmccabe]

Thanks guys. I plant to block the first coat with 1000 using a block that is fairly rigid. I guess I can see why Barry would use 400 but that does seem darn course !

OK, sounds like the wave I have seen OFTEN is probably Urethane Peel

Rich

[beemdubya]

If you look at this pic u will see my florescent lights and how the edges are wavy.. this kinda shows that urethane paints arent flat.. that was only sanded with 2000 grit and buffed.

[rrmccabe]

OK, thanks for the pic.

Maybe, I will try 600 or 800 on first go and then move up. I really would like to get that out (on this car anyway).

Rich

[roger1]

Originally Posted by beemdubya

Yea. urethane wave is what my old shop teacher used to call it.. im still trying to figure out how those 400 scratches are gonna come out.. but i guess if u sand one panel with 1000 after 400 for quite a while it should come out at some point..

Maybe. But, how can you tell until after you polish it?
I don't think you'll be able to see those 400 scratches during the sanding process. Only after you buff.

I know Barry knows what he is doing, but I don't know how this is done successfully. However, I only tried this on SS urethane. Could clear be different?

[baddbob]

One option is to start with a coarse grit and block by hand then switch over to a DA with finer grit and sand until all of the straight scratches are gone, this way you know the coarse grit scratches have been removed.

Or change sanding direction.

If you use an extremely flat and rigid block and only apply one thickness of paper to it (not wrap the paper around and around) you can get some really good results with 1000 or 1200 on the initial cut. 1/4" thick plexiglass is ideal and can be sanded completely flat with rounded edges and corners, I've got a few of these made up in different sizes that I use for colorsanding.

[mrcleanr6]

i will usually block with 800 first but use self adhesive paper on a ridgid block. i find if you dont use stick it paper the suction from the water just pulls the paper to the paint surface and rides the waves so to speak.

[baddbob]

I'll have to try the stickit paper interesting , what brand are you using? Bob

[BondoKing]

Bump.. I would like to know what kind of paper too... Are you using DA paper?? Never thought about the paper moving aound... good post

BK

[beemdubya]

Ive used regular 3m wet/dry sheets and cut them to size and used 3m spray adhesive to hold it to the block. thats prolly the easiest way

[BarryK]

The 400 wet will come right out with the finner grits of paper.
My sons Dark blue Corba deck lid with three coats of clear I first sanded with a 320 da to get rid of all imperfections as there is no hiding anything on this car. Then went to finer wet sanding grits and buffed, it buffed great and is slick as can be.

This car was done in a way I don't like to do but were under the gun time wise. I don't like the idea of more than three coats of clear a day and I would like to have wet sanded and re-cleared and I would have liked to let the base set overnight. I feel like Boyd but did not have a choice.

[mrcleanr6]

Originally Posted by baddbob

I'll have to try the stickit paper interesting , what brand are you using? Bob

i use a da with a 5" stick-it pad and a spray bottle. start with indasa 800g 5" discs. once the whole car is smoothed out i switch back to the hook-it pad and a soft interface pad and use the 3m 1200 dry discs. i actually do the 1200 dry. with this i go over all the 800 areas and the glossy curves i couldn't get with the 8. thats where i stop and bust out the buffer. wool pad with perfect-it 2 compund then foam pad glaze. normally on a bike or anything else i would wetsand to 2000 but there is something about dry sanding with the 12 that makes it just as easy to buff out as the 2000 wet and the clear smooths out just as well so i figured why waste my time going further. this is the fastest method i have ever found.