Here's yet another advanced technique in the general "craft" of detailing, usually more at body shops but all top detailers usually come across this at some point in their career.
Removing runs, sags and dirt nibs
How to use Meguiar's Unigrit Sanding Blocks to remove runs and dirt nibs in paint
Meguiar's Unigrit Sanding blocks are solid blocks of precise, uniform grit particles that can be used to remove above surface paint defects like runs, sags and dirt nibs protruding out of the paint.
Dirt nibs = dirt particles or other contaminants that land or lodge into fresh paint before it hardens to dust free or tack free.
Meguiar's Unigrit Sanding Blocks are available in 3 different levels of aggressiveness.
#1000
#1500
#2000
Dressing or shaping Unigrit Sanding Blocks
Before using a Unigrit Sanding Block, knock down the sharp edges by rounding them off this will prevent you from gouging or scratching the paint. Remember, if you're working on fresh paint, (whee these sanding blocks are normally used), the paint will tend to still be soft as it hasn't fully dried and hardened.
To dress your Unigrit Sanding Blocks you can use a more aggressive sheet of sanding paper to round the edges.
Rinse off grit particles
After dressing your Unigrit Sanding Blocks, it's a good idea to rinse them off before placing them in your bucket of water to prevent contaminating your water source.
Soak before use
Before using Meguiar's Unigrit Sanding blocks first soak them in clean water until they sink. This is a sign that the blocks have completely saturated throughout with water.
Keep your Unigrit Sanding Blocks in a bucket of water when using them so you can quickly and easily dunk the blocks into the water and rinse any particles off as you're using them. When not in use, Meguiar's Unigrit Sanding Blocks can stored in water to keep them saturated with water and ready to use. Change your water often to help prevent contamination.
Lubrication
You can add a few drops of soap to increase lubricity in the water. If working in a body shop (fresh paint environment), be sure to use a body shop safe soap.
Grit Guard Inserts
To trap any loosened particles of paint or grit particles that wear off the Unigrit Sanding Blocks you can place a Grit Guard Insert in the bottom of your bucket. Some people even use two Grit Guard Inserts to help ensure any abrasive particles on the bottom of the bucket don't migrate.
How to remove a run or paint sag
To remove a run, you want to use the side of the block and only sand on top of the run. If the run is thick, you can place tape on the sides of the run to prevent you from sanding on surrounding paint while knocking down the run. At some point you'll have to remove the tape and at this point focus on the task at hand and hold the block in such a way as to only sand on the high points of the run.
Back and forth direction
Holding the Unigrit Sanding Block firmly, use a fast back and forth motion to sand the run down flat.
Use fingers as a guide
On the panel below, the run was just below a raised body line. The run was too close to the raised body line to use tape to cover the body line so instead I placed my fingers on the raised body line and used my fingernails as a guide or bumper to prevent my hand motion from running the sanding block over the paint on the raised body line.
Here I've sanded just a little and then stopped to take this picture as the sanding marks have made the run easier to see and capture on film.
The section above was sanded flat and then the sanding marks were buffed out using a compound and a wool pad on a rotary buffer. Next I continued to move down the fender sanding the run flat.
After the majority of the run has been sanded flat I re-sanded the entire area using a Meguiar's 3" #3000 Unigrit foam backed sanding disc on a Griot's Garage 3" Mini Polisher to refine the sanding marks left by the Unigrit Sanding Block to a more shallow depth to make removing faster and easier and without generating as much heat.
End results...
After the orange peel, runs and dirt nibs were removed, the paint was compounded and machine polished and after 30 days air dry the paint was sealed.
I always use Grit Guards in my bucket when use sanding blocks to remove runs, sags and dirt nibs.
rops: Yes, I used them to dry pads, sponges, etc.
