What is guide coat for?

Guide coat is used by pretty much every body professional, but what is it really for?  Are you using it correctly, and is it helping you like it can and should be?  

Guide coat really has two purposes; to show you low areas while you’re block sanding, and, most importantly, to show you scratches.  This is why it’s very important to use plenty of it, and make sure it is applied everywhere. 

When absolutely no scratches are missed as you’re sanding, it makes it possible to use less grits, saving a lot of time and sanding steps. 

Before applying guide coat, make sure the panels are clean and dust free.  Blow it off good and clean with wax and grease remover.

Mirka dry guide coat is really good.  It comes in black and white.

Once the guide coat is sanded completely off, wet it down with wax and grease remover to check for remaining scratches.   When the guide coat gets wet, it is much easier to see. It is hard to see in pictures, but below are two examples. Circle the areas with a pencil that need to be sanded more.