Technical > Body work

Bog done... what next?

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PeterAllen:

John (and other pros) - I have used filler to get what I feel is the new profile of the door skin but I want to know where I go next to ensure the surface is perfectly smooth and flowing. There is nothing worse than looking along the side of restored/modified cars and seeing a 'cellulite' surface.

Retro Z:
Go over the filler work with 400 to get rid of deep scratches, blow out dust and wipe with prepwash..dont use water. Then spray on some high build primer (hi-fill) once dry mist on a guide coat with some black paint. Then wetsand with 800. Repeat filler or hi-fill if necessary then prime and paint.

Thats what I do in a nutshell.

Retro Z:
Oh and remember to use a block when you sand to get a flat uniform surface.

Sirpent:
Hi Peter,

With respect to Candy, I would suggest a few more steps prior to priming etc.

If you have finished the major sanding and want to save a SH*T load of time effort and material later, and get the flatest surface you can minus the deep grazing scratches of the main sanding, then the best way is to do the following.

#1 Get yourself a VERY flat piece of ply wood, pref Marine ply, it should be the size of a sheet of sand paper folded in half and 15mm smaller around the outskirts than what the paper is, in other words if you get it right the folded sheet of paper should fold around the edges of it, the idea is that you have a paper platform that allows you to hold it and the paper with an open hand at the finger tips.

#2 Go to the kids old school desk and find a blacklead pencil (soft 2b-6B) then scribble all over the body filler area you want to surface, cross hatch it vertically and horizontally with lines 5-10 mm apart, this is how I taught my apprentice to surface body filler and I still do the same today.

#3 Now position yourself so you can execute long strokes (SIMON don't bother with any filthy remarks) on flat panels always work horizontally each time you sand over an area move down a fraction on the next run so you have an overlap, on curved panels also sand in the same horizontal plane but at 30 degree sweeps and follow the contour of the panel, I usually use 320 white oxide paper for this task, anything more is overkill.

What you will see is the lines you scribbled start to disappear, you will most probably also see small patches or low spots with the gridded lines still visible, never ever works on them in one spot attempting to delete them, continue the elongated sweeps over them and the areas that have already lost the pencil marks, its these area's around the low spots that are still to high in reality.

To see if you have accomplished what I have prescribed, take an old T-shirt (Cotton) and use a layer of the material across the palm of your hand, gently wipe over the area you have sanded, close your eyes (I'm serious) and concentrate on feeling the surface, you will either feel a flat surface or imperfections, the reason for the material is that your bare hand actually sticks to the surface as you cross it and this diminishes your sense of touch, the cotton wool actually stops this yet allows you to sense what the surface is doing.

#4 If you come across high spots of metal coming up as you execute the above, stop immediately and take a pick ended finishing hammer (point ended hammer) and dolly and just gently ease the high spot down with multiple gentle taps, then continue sanding, there is no need to refill these lowered high spots when you are done as the highfill should do the job.

Last, after its all done, take some prepsol and wet the surface horizontally then gun sight the panel, if all is well you should see a very flat although dull reflection in the panel.

NEVER EVER rub down the filler with wet and dry paper and water, filler is porous and the water will make its way to the metal below which could cause drama's later.

If you take these steps, you will use less hi-fill (I prefer EP these days) spend less time doing the final surfacing and end up with a much better pre-prime surface and eventual finish.

Cheers

John

Retro Z:
+1 ^^ ;)

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