Final sanding of BODY FILLER. [Archive] - Team Camaro Tech

: Final sanding of BODY FILLER.


ifishaholic
Nov 20th, 03, 07:43 PM
O.K. folks, lets hear your opinions on what grit to sand this stuff before application of the primer surfacer, 80 or 120 grit.

Or could you get away with just 40 grit, do three full wet coats of primer surfacer, then apply on top of the surfacer a scim coat of "icing" over the body filler areas to fill the 40 grit sand scratches and block sand with 120 grit; Then follow this with the next three coats of primer surfacer?

I would greatly appreciate any expert opinions on this; (ie. Martin Sr?)

MikeM79
Nov 21st, 03, 04:53 AM
I don't like the idea of relying on icing to fill up sanding scratches that can be eliminated from the get go.

I finish fillers with 220 grit and sometimes will even use 320 or 400 on the feathered edges of some repairs. That may be overkill, but it doesn't take very long.

Also, it seems as if you think that the more primer you can get on the car the better the job will be. The object is not to apply six coats and sand off four. Using fewer coats of primer costs less, but requires the underlying surface to be absolutely true.

Primer's job is give the paint something to stick to, not to be a "liquid bondo" to conceal a wavy substrate. Sure, block sanding the primer will reveal some minor low and high spots and sometimes just one more shot of primer over a low spot will do the trick. This is okay, but don't rely on it to do the filler's job.

The same thing happens in house construction. The crew that hangs the sheetrock cuts some corners because they think the guys that tape and "mud" will "get it", the guys that tape and "mud" cut corners in hopes that the painter will "get it".

BBCamaro
Nov 21st, 03, 05:05 AM
I like doing my bodywork and on first coat hit it with 40 grit, shape it, then 2nd coat sand with 80 grit, feather it out, then with some 180 or 220 go over area quickly one or two passes just to knock down the 80 grit scratches, then i like to apply 2-3 coats of urethane primer, then block sand, 98 % of the time i block sand then prep for paint, if there is still a low area use a polyester glaze, and re prime spot to smooth, sometimes you can get into trouble sanding with real fine grits, IT CAN RING OUT so you see whole repair area, but it can be done, for the average guy i would stick with 40-80 grit then 2-3 good coats of primer with at least 24 hrs inbetween spraying and block sanding, using a guide coat is also a very good way to see any low spots, good luck
Jake

sevt_chevelle
Nov 21st, 03, 08:41 AM
Using a icing glaze or poly putty is NOT cutting corners when doing a filler job. The poly putty is meant to be used as a final skim coat of product to finish off the repair. It sands easier, feathers out nicer, spreads great, has next to no shrinkage.

Relaying on poly glaze to work like a regular filler is where you get into trouble, using it as a finisher on a filler job is a VERY acceptable repair method.

The ONLY difference between a poly glaze and regular filler is the amount the filler material(TALC) is ground up.

Every filler job I do gets a skim coat of poly glaze. I mainly use 80 grit to cut the regular filler then apply my poly glaze. Allow the glaze to cure then hit it real light with 80 to knock off the hard layer on top then switch to 180 grit for final shaping.

Leaving those 36 or even 80 grit scratches in filler can come back to haunt you. All that does is give the primer MORE surface area to try and fill. Final shpaing with 180 leaves alot less of a scratch to fill...Eric

shoddy_F-body
Nov 21st, 03, 12:32 PM
I agree with the opinion that you should not rely on primer to fill 40 grit scratches.Primer shrinks(no matter what brand) and if you have it filling in 40 grit scratches they will show after a while. As far as icing i haven't used it on body filler since i started using 2k prime about ten years ago. I use it other places though but have eliminated the need for it on filler by using this method. Once i have the area as perfect as i think i can get it,finished off with 80, i put on a real tight,smooth coat of plastic.Then longboard it with 120,then a quick swipe with 180 just to knock out the 120 marks.Then prime it,waiting inbetwwen coats for it to COMPLETELY flash,and don't bail it on. If your not in a hurry let it sit a couple days before blocking and you should have no problems. graemlins/thumbsup.gif

MARTINSR
Nov 21st, 03, 03:11 PM
Shoddy, if you don't use a polyester putty to finish your filler and are sanding it with 180, you don't know what you are missing!

Polyester putty is the ONLY way to go to finish filler, the "skim coat" if you will.

Let me repeat Erics point, there is NOTHING, but NOTHING wrong with using polyester putty. We are not talking about some junk out of tube for goodness sakes, we are talking POLYESTER putty. POLYESTER just like POLYESTER filler such as RAGE. They are one in the same with the basic difference being how fine the talc has been ground.

TRYING to fill 40 or God forbid 36 grit scratches with ANY primer other than, you guessed it, POLYESTER primer is WAY, WAY WAY out of line. A urethane primer is NOT going to properly take care of those deep scratches.

120 or 180 scratches will easily be filled by most any urethane primer with no shrinking IF the primer is applied properly.

shoddy_F-body
Nov 21st, 03, 03:44 PM
I have used it before,Icing,Evercoat, all that stuff is nice but its not cheap at around $20 a quart.But of course if the shop is supplying it i will use it but if i'm buying i can do without it. ;)

ragtopman
Nov 23rd, 03, 04:32 PM
I always use a polyester putty to finish my work. Sanded with 80 grit, then gone over it with 180, prime, block it and re-prime. You will never go wrong. graemlins/thumbsup.gif