• Having site issues? Contact Dub@southernPolyurethanes.com

Fixing runs in SPI Base before clear

#1
Hi,

What is the right time window and procedure for fixing runs in SPI base before doing clear?

I've read that I can wait for the base to flash, then wetsand it to get the run out, then spot paint it with the base. But I'm not sure how long I have to wait before the wetsanding part.... rubbing water into uncured paint seems like a horrible idea to me.

Thanks,
Sal
 
#3
I can wait... I'm not painting until December :)

Just trying to get all my ducks in a row beforehand (so it isn't an emergency when I inevitably screw up)
 
#4
Base should never be put on so wet that it runs, so it should be a very rare occurrence. But, wet sanding is not to be feared. Most base coats won't sand very well and will tend to gum up the sandpaper, making wet sanding almost mandatory. The exact procedure would vary depending on the severity of the runs and how it looks once sanded.
 
#5
Base should never be put on so wet that it runs, so it should be a very rare occurrence. But, wet sanding is not to be feared. Most base coats won't sand very well and will tend to gum up the sandpaper, making wet sanding almost mandatory. The exact procedure would vary depending on the severity of the runs and how it looks once sanded.
Everywhere I read says to put base on lightly... but the tech sheet says "With proper gun adjustment, this base should be sprayed using wet coats. "

What is the minimum time I should wait after spraying the base to wet sand?
 
#7
Thanks for the link to the guide.

Followup question...

If I get a run in the base, I wait overnight to sand it and then respray that area with base. Then it says to wait overnight again before doing the clear.

This means that the areas that weren't fixed and recoated have been sitting for 2 days between base and clear. Is that right? Or do I need to recoat the whole thing when I fix a run?
 
#8
Thanks for the link to the guide.

Followup question...

If I get a run in the base, I wait overnight to sand it and then respray that area with base. Then it says to wait overnight again before doing the clear.

This means that the areas that weren't fixed and recoated have been sitting for 2 days between base and clear. Is that right? Or do I need to recoat the whole thing when I fix a run?
If you get a run on base coat, wait 30 mins and then grab a piece of wet/dry sandpaper and spray it with 710-1 W&G remover then immediately sand the run out, have clean paper towels ready to go next to you so you can wipe off excess sanding residue and to dry the basecoat quickly. This will give you way better lubrication than using water and won’t harm the basecoat at all, you can do it multiple times with the same piece of paper that you can rinse off with the W&G remover spray bottle or switch to new fresh sandpaper. Barry gave me this info years ago and it works extremely well, you should try it on some scrap metal and put some runs on purpose and practice.
 
#11
Yeah, 700 is too strong, believe it or not. In my opinion, the method @Jorge M. describes is suited for a production job where things have to be kept moving. I would probably wait longer and use heat if possible to make sure the solvents are driven out of the run. If the run is not dry and still gummy inside, the chances of screwing something up are much greater, especially if there is fresh sealer underneath.
 
Top