How To Master Sanding Bodywork Repairs!
"Discover The Methods of Auto Sanding - Using an Short Sanding Block vs. Long Sanding Blocks and...
How To Correctly Sand Auto Body Filler so That All Body Panels Are left Perfectly Flat, Smooth and Flawless"
Since you now have the panels free of any surface damage and aligned properly, you're still not ready to reach for your spray gun.
Before You Continue:
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Can you find any other minor dents or surface damage present on any of the panels? |
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Do all of the panels such as the doors have a series of vertical lines in them? (This is especially important if and when another door came into contact with your door panel). |
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Is the overall texture of your vehicle still a little rough? Try running your finger tips over all of the panels on your vehicle. You'lll be surprised at how much auto body work perfection depends on your fingers and sence of touch. By feeling the panel with your hand periodically while sanding it will give you a good indication of any high and low spots that you may need to pay attention to. |
If you answered 'yes' to any of these questions above, it means that you have some more work ahead of you before you can start reaching for your spray gun.
You might want to take out some sandpaper and your sanding block and take care of all those imperfections. Trust me, it will be more than worth your effort once you have applied the base coat and clear coat.
Get this done nicely and your job will look like a mirror!
*To Get PRO Finishes*
You must use an auto sanding block
You hand isn't flat and because of the irregular pressure your hand will therefore generate you should not sand without using some kind of auto sanding block. Using your hand alone will tend to make the panel wavy as more pressure will be applied by your fingers and less in the areas in between them.
In some cases, later when you understand how your hand works with auto body tools and sand papers, you may start to watersand panels without using a block at times. In some of the VIP videos you may see me sand without a block at times. This is because I know what I am doing and I know of what to be aware of.
If you're a total auto body and paint beginner, stick to using a block. You won't have a chance to mess up.
How To Use Auto Sanding blocks.
The correct method of using auto sanding blocks is in all directions. Do not simply maneuver them in a back and forth direction from the front to the back. Move them up and down and crossways diagonally too, rotating the board or block as necessary for ease of operation. We cover this in great detail in the VIP course.
By maneuvering the auto sanding board or block in different directions will guarantee that all areas are sanded smooth without grooves, valleys or perceivable patterns.
Sanding Using a Long Board
Using a small sanding block on a wavy panel will simply make the block ride over these waves. The panel will indeed become smoother but it will still be wavy.
Therefore, instead of using a short sanding block, use a long sanding board. This will bridge the high and low spots of the panel, smoothing out the wavy panel texture.
The secret to achieving the straightest and flattest possible surface upon which to apply paint is to use a long sanding board or block with progressively finer sandpaper.
After you rough sand using relatively coarse 80 - 100-grit sandpaper by hand or straight sander, then use an air sanding machine with 150- to 320-grit sandpaper.
It's important to remember here that when auto sanding a panel that curves in one direction from top to bottom say but is straight from front to back, auto sanding is mostly performed by moving from top to bottom, up and down the panel obviously with the long sanding board or air file held horizontally against the panel.
By using a long board across the crown i.e. from front to back with the long sanding board or air file held vertically against the panel, you would tend to flatten the curve, this isn't the desired result you want to achieve.
Further Benefits of Using a Long Sanding Board - Straight Sander
In addition, by using a long sanding board or air file will also give you a better indication of the high and low spots than a smaller sanding block would.
As we visualized earlier, the longer sanding board would span the high spots and bring them down to the same level as the low spots, where the smaller sanding block would simply ride over the wavy panel.
Although sanding blocks are available commercially in various shapes and sizes, you will often need to improvise to access the particular area that you are sanding.
To finish, a normal-sized sanding block can then be used to touch up the edges of areas where you applied the auto body filler. Remember, you can never sand too much. What may look great in raw auto body filler will quickly show any pinholes or other blemishes when you apply a coat of primer-surfacer.
Sanding Auto Body Filler Repairs
No matter what type of surface you intend to paint over; auto body filler or an existing paint finish, some auto sanding is going to be needed.
This stage of the whole repair process is one of the most important and is why professional auto painters will spend up to 95% of their time on making sure that surfaces are perfectly prepared for the application of paint; every blemish or surface imperfection will be magnified by coats of paint.
The top layers of auto body filler are sanded primarily using 80- to 180-grit sandpaper. This will flatten out the rough spots and get surfaces smooth and close to being even. Next, 240-grit sandpaper would be used to make the finish even smoother and flatter.
After you have flattened the area down using 240-grit sandpaper, removing all of the high spots and other surface irregularities; finish sand by using 320-grit sandpaper to remove any left over sanding scratches and minor imperfections.
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Coarser grade sandpaper shapes auto body filler until it is flat and blends with adjacent panels. |
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Finer grade sandpaper focuses on surface texture & smoothness to get ready for primers. |
Don't stop until the entire area is faultlessly smooth and flat; it needs to blend perfectly with the surrounding surfaces.
Benefits of Using a DA Sander
You can cut your bodywork time drastically by sanding quickly and uniformly using a DA (dual action) sander. A DA sander has two modes of movement: either a rotary action for rapid material removal or random orbital motion for fine finishing.
You should practice first using an old spare body panel if you aren't familiar using a DA sander. They are really easy to use once you get the hang of it and you'll love having one. In my book it's one of the most used tools in auto body repair and painting.
Be aware, even though DA sanders may not appear to be moving that fast, they will still remove large amounts of filler material very quickly.
Once you are satisfied with your auto body filler repair, use 320-grit sandpaper to develop a well defined visual perimeter around the entire repair area.
You will end up with a series of rings that form around the repair area, exposing a band of bare metal approximately one inch wide maybe, then bands of roughly equal width exposing the epoxy-primer, sealer, primer and paint.
Your aim is to develop a smooth flow from the top surface of the auto body filler area through to the top surface of existing good paint.
This will permit fresh applications of undercoat material to match the same levels as those existing materials on the rest of the car's surface.
Additional coats of primer material will also be sanded to a point where the only difference in depth between the existing painted surface and the repair area would be the actual thickness of the existing paint.
You will then be able to apply final color coats in thickness equal to the rest of the paint finish for the best possible blend, color tint and texture matching the surrounding paint finishes. This process is referred to as feathering in.
Cleaning Sanded Surfaces Prior to Applying Undercoats
After you've completed sanding or scuffing the surface, make sure you take your time to clean it thoroughly to remove all surface debris.
Most professional auto painters use an air hose to blow away the layers of sanding dust left behind from sanding.
Then they would use wax and grease remover to thoroughly clean the surface down with.
Simply dampen a clean cloth with wax and grease remover and use it to thoroughly wipe off all body surfaces in the area to be painted.
To enhance the cleaning ability of wax and grease remover, follow the damp cleaning cloth with a wipe from a clean, dry other cloth. This dry cloth would pick up lingering residue and moisture leaving behind a clean, dry surface. Always use a new piece of cloth on every panel.
Heavy duty paper towels are excellent for this purpose. Being disposable they are sure to be clean if they haven't been exposed to any dirt. With re-usable towels or cloths, you can never be certain they're 100% clean.
Mild solvents in wax & grease remover loosen and dislodge particles of silicone dressings, oil, wax, polish and other materials adhered to the surface.
Finally, wipe the vehicle down again with a tack rag in your garage or paint booth just
before you start spraying any paint material.
Good luck!
P.S. To see all of this on videos Click Here!
