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Base Color Sanding - Part 4

Posted by Jay Schneider. Filed under Paint.
March 19, 2012

An experienced body man’s sanding technique is about as individual as snowflakes – they are all different. Peering into an experienced body man’s tool box will most certainly reveal dozens of hand-made blocks for just the right angle or hard to reach spot. 

There are however, certain rules we can establish to help insure against inflicting further damage into the surface from poor sanding techniques. Proper angles of attack, excursion pressure, grade of paper being used – all have a significant play on the end result. It is suggested that all data sheets and instructional information be read, provided by the manufacturer, prior to starting your project. Although there are industry accepted standards for sanding every conceivable surface known to man, every product is different and has certain that must be adhered to.

 A very critical aspect to sanding and key to the overall look is in reference to the angle of attack or direction towards the un-sanded surface. For example, straight line sanding means just that – any deviation from it can create concave or convex waves resulting in a poorly finished surface. Straight line sanders and blocks are abundant and come in different widths, lengths and variations – they are available in hand held manual blocks, as well as pneumatic tools. Straight line sanding is critical for what I like to call “wide open spaces”. When one wants a very flat surface, this is the best technique to insure one does not get sea sick when inspecting a flat panel full of waves due to poor sanding techniques J

Bias sanding is another very important technique to acquire. This technique is 1) used when sanding over a curved surface – like a fender for example; and 2) performed by attacking the surface approximately using a 45 degree approach angle with relation to the crest.  Bias sanding reduces the possibility of creating a flat spot on top of the crest.  With a little practice, you will know what technique to use and when to use it.

Orbital sanding is probably the easiest and most effective type of sanding action however it has its drawbacks – that being the curly ‘Q’s” it leaves behind. Starting out with too aggressive of a paper will surly set you back a few steps. Orbital sanding can be used for fender and straight line sanding when performed by an individual with more experience. However, for knocking down heavy applications of body filler or primer, it really works out pretty well because you can follow up with a better, more accurate technique like straight line or bias sanding. Orbital sanding is a process whereby the papers’ aggregate is constantly attacking the surface at different angles thereby placing random sanding marks into the surface – in my own practice; I will use an orbital sander to the point where I know I have enough surface below to remove any marks left by the orbital sander….. proceed to remove them,  before going on to the next step.

All of this takes a little practice – the worse that can happen is you’d have to re-prime or re-apply body filler - be patient it’ll all come together before you know it! Knowing how hard you can aggressively attack the surface will pay off hundreds of times…..been there done that J

Keep the blue skies up and Happy Motoring!


Scott S. Mc Lain

Vice President

Lake Country Mfg.


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