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Sag in clear still visible.

#1
I’ve got a sag in my clear that is still visible after sanding with 600. I’ve blocked it with a hard block dry. It looks level until you refine the scratches and buff and it’s still there.
What can I do to get rid of it?
I’ve sanded out runs before but this one is giving me fits.
 
#2
I’ve got a sag in my clear that is still visible after sanding with 600. I’ve blocked it with a hard block dry. It looks level until you refine the scratches and buff and it’s still there.
What can I do to get rid of it?
I’ve sanded out runs before but this one is giving me fits.
Can you post some pictures?
 
#3
I will this afternoon when I get home from work. You have to have it in just the right light to see it. And can’t feel it.
 
#4
Letting it age a little before final sanding and buffing usually helps.
The run is thicker clear, it cures slower so it's softer, the softer will sand differently from the
surrounding harder clear. Let it age a day or two then sand it again.
I usually try to level it about 95% of the way real soon, then let it cure another day or longer
before final sanding. A heat lamp helps, but the longer the cure the better.
 

Barry

Paint Fanatic
Staff member
#5
I take 320 da paper and fold in half.
With two middle fingers i sand the run from floor to ceiling.
All im sanding is the high spot and when it gets to the clear where its level, i go to 1500 wet with paint stick or 4 inch block to make sure perfect.
 
#7
Another question out of curiosity. I’m thinking about putting three more coats of clear on this door. If I don’t get the sag completely out and then put three more coats of clear on, what will the consequences be?
 

Chris_Hamilton

Trying to be the best me, I can be
#8
Set it on the sun for a full day. Then go back and re-block it. 600-800 grit wet. Use a firm block. That should take it out completely. Can you feel it with your hand? What coat did you get the run in? If it was the first or sometimes even the second it can make getting it completely out more difficult.
As for your last question I haven't dealt with this situation for a long time so I am not 100% confident in this, but everything else being equal it should be OK if you re-clear then color sand everything again. If there is any doubt or you got the run in the first coat the you may want to block it completely out (basically sand off the clear in that small area) spot prime that area to build the millage back up to the surronding area, then block it, spot your color in and re-clear. That shouldn't be neccesary but it is an option.
 
#9
You can’t feel it at all. You can only see it in just the right light. Like lights off in the garage with the door open. Then you can look across the panel as you face the outside light. Looking at it that way it’s obvious.
I’m bright sunlight you can’t see it.
I’m not sure which coat I got the sag in. Can’t remember. I was thinking second or third but not sure.
 

Chris_Hamilton

Trying to be the best me, I can be
#10
I would think it's simply a matter of blocking it completely out. It's not that hard to think you got the run out completely, buff it and still see it. It's happened to me in the past. Probably just blocking it some more will do the trick.
 

Chris_Hamilton

Trying to be the best me, I can be
#13
Without seeing it I would say that if you have blocked it several times now (and assuming you are doing it correctly) and are still seeing it then yes you are getting very thin in that area and you may need to do what I said in my above post. I would imagine that you got the sag in the first coat and that is why it is being difficult. That's the only thing that I can think of if you have blocked it several times and still see it.
If it was me, I'd sand with 400 wet, the area where the sag is extending out a few inches around it. Probably do that until I saw some color(base). Then clean it, mask it, wipe it down, and spot prime that area, letting it feather out just a bit into the surrounding area. Block the primer and spot some color in, then re-clear the panel. Probably not what you want to hear but probably the most prudent way to proceed.
I will say that re-clear only may work as well but not being able to lay eyes on it, the safest thing for me to recommend to you would be what I suggested. I've seen guys trying to get a run out then reclear it and you can see the area that the sanded will show up as a small dip or low area.
Keep asking questions if you have them.
 
#14
Ok thanks again. I may give it a few days and block that spot some more.
I really believe I could spot some base in that area now (over top the sag) and reclear the whole panel and that would work too. Because you can’t feel it and I’ve colored the entire area with a sharpie as a guide coat and it blocks out flat. But in just the right light you can see the ripple of the sag.
I’m in no hurry as this is a project I’m doing for myself.
 
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