Sanding EM Body

ronzara · #1 (**permalink**) 05-22-2002, 10:26 PM

Hello Everyone.
Well the time has come to put the body on the car. I have sanded the molding seams down smooth on the car, they look and feel nice and smooth. The question I have is:

What should I use to sand the rest of the car?

My manual says to dust the body with red oxide primer then "block sand" to find high/low spots that should be worked with bondo/resanding ,... this sanding will also prep the gel-coat to accept paint.

This makes sence,... I have a 3"X5" Block and a 3"X 8" block..... but I am afraid of making the body wavy with uneven sanding.... Is there something I need to know here??? My body doen't appear to be too far out of straight.

Any suggestions or any web-site where I might get more technical info??? Thanks,
RZ

sfry · #2 (**permalink**) 05-22-2002, 10:43 PM

Ron,
Red Oxide is a color of a lacquer type primer. This is a 1970's technology product. Use a high build urethane like Duponts 1120s or PPG K36. This product dries by chemical reaction vs. evaporation of solvent. In a nutshell you will get much better results out of these products vs a lacq. type product. After the primer has dried you will need to then spray a guide coat over the primer and block sand until the guide coat dissappears. Call me if you need more clarification. I could go on all night about block sanding.

Shannon
(408)210-1048

Bob Putnam · #3 (**permalink**) 05-23-2002, 05:19 AM

And... Preparation is everything! Clean the 'glass impeccably before you apply any primer. Others will have the best materials and methods for this (I hope).

It sounds like this is your first bodywork project. I hope you've got the touch of an artist.

I don't.

Double Venom · #4 (**permalink**) 05-23-2002, 06:18 AM

Nothing more to add here. Shannon and Bob are right on!

We use the Dupont products that Shannon suggested, (definately stay away from any lacquer based products), then we just use a black, red, gray, what ever contrasting spray can paint, and spray a light mist coat over the entire car. This will give you a good guide coat for your block sanding.

One more re-iteration - do NOT touch the body before cleaning it! No sanding, no spraying, just wash it with a good body prep.

The reason for this is the mold release compound that remains on the body when it is pulled from the mold. If you start sanding on it before cleaning you can and will just bury the release agent into the glass.

Paint does not do well covering up wax! Good luck and post some pictures for us if you can!

DV -- We need your help and support! Have you bought your raffle tickets yet? Full TV coverage, 250 plus Cobras, 3 days of rolling fun, it just can't get better! Are you registered?

niles · #5 (**permalink**) 05-23-2002, 10:22 AM

Start by washing the get down with a wax remover. Then "longboard" the gel first. You need to start with an the 18 in longboard. Your inclination that the body is flat and smooth is wrong. It is full of waviness etc that you wont believe until you been thru the process yourself.

I estimate maybe 150 hr total and that includes blocking the jell coat, 2 coats PPG epoxy sealer/primer-blocking again. Looking perfect! Figured one more coat of high build and it would be ready for final blocking. No way!! Everytime you get out the 3M guidecoat and block it; it just gets better and better and flatter and flatter.
I've just finished putting on 4 additional coat of primer and sanded almost all back off. BUT; it just keeps getting smoother!
All this priming and block sanding it easy; two suggestions: good gravity fed gun and lots of blocking; it takes about 4 blockings until you finally get the technique and all the different blocks(hard rubber, soft rubber, rubber hoses and spongs) figured out. I now can completely block the car in about 2 hrs. Only hard part is getting the doors and gaps right. This would take a hr to write up. Grive me a call (eve) 850 678-3306 and I'll walk you thru it. Not hard
grover

Bruce Botti · #6 (**permalink**) 05-23-2002, 09:22 PM

Ron,
The only thing that I can add is to take a look at www.autobodystore.com. This is a great site for novices and professionals alike. I find them to be very friendly, professional, and helpful.......gee....just like this site!
Take care,
Bruce

grumpy · #7 (**permalink**) 05-24-2002, 12:54 PM

When you are to this point,
1, Block sand the entire body in 180 (grey - dry paper) removing a bit of the gelcoat. Do this in 45 degree angle long strokes. Completely sand the entire area to be painted.
2. Blow on a little primer that is an opposing color (grey gel /red oxide primer, black gel/grey primer) and take the 16.5" flat board hand sander (grey - dry) and sand in long strokes at 15 degree angle to travel over all the surface. You will be surprised how many low and high spots show up. The primer will remain in the low areas.
3. Then hit it with a very heavy coat of filler/primer that will match your final coat shade. Re-sand with 220 or finer grit (grey - dry paper) in the same fashion as step two, only do not remove down to the gelcoat. Final prime if you're happy with the smoothness, and then get out the small rubber sanding blocks and sand the entire body with 45 degree angle strokes to each other until your'e satisfied. Use a sponge rubber with the 220 grit pad and the heel of you palm in the inside of radiused and shoulder areas.
4. From here it's the finishing sequences you need to go thru.

The manual is still correct in using the lacquer based primer for "leveling start prime to look for waves", it's quicker, cheaper, and dusts up easier. You will find lacquer thinner at less than 6.50 a gollon at Lowes, you'll need it for clean up anyway.

You'll be surprised how you will get the "feel" for a truly smooth surface after the above steps. Color coat and use "wet sanding" for the first time to look for additional waviness.

Grumpy

rbray · #8 (**permalink**) 06-20-2002, 02:12 AM

After reading this thread I have decided to take a crack at doing the prep work on my EM.
I have cleaned and degreased the body as you have suggested.
My first task is a block sanding with 220 grit.
The body is seamless, but it does have some mold lines in it.
After applying some spray paint and resanding I discovered that I put some flat spots in the gel where I sanded down the mold lines. I am now in the process of applying Everclear galazing and restanding.
Thanks for all of the information and I hope you don't mind if I ask some questions along the way,
Roger

scratch · #9 (**permalink**) 06-20-2002, 08:47 AM

Ronzara,
...your blocks are too small (sanding...not engine!) Niles has it right. You need a long-contour sanding block that FLEX's.

You might have noticed that the cobra body has no flat areas, unless you sand too long in one spot.

Be prepared for about 5 weeks of work, and look for the "waves" by setting up lights downstream. It's a hassle but better you find them now than after spraying.

PS... I cuss in church stronger & faster than you...

scratch

rbray · #10 (**permalink**) 11-10-2002, 11:16 AM

I did some sanding on the mold lines of my EM last night and ran into a problem. On the advice of the guys at EM I applied some Everclear to the lines before I started sanding. The lines are now very smooth, but the Everclear still seems to be a little soft and if I dig at it with my finger nail it comes off the car. Just to make sure I didn't make a mistake mixing the Everclear, I mixed up a batch on the work bench and let it dry overnight with the same results. Is this the way this product is intended to work, or am I doing something wrong?