The Stovebolt Site Forums The Shop Area Paint and Body Shop What to use when block sanding?

Hello!

A few months ago I posted about some disappointing results after sanding some bondo on my '59 Apache. After hours of sanding, and a spray can coat of paint and primer to protect things, I could still see the repair if I looked at the panel at an angle. I realized that I should have sanded more, and many told me that I sould "block" sand.

This may be an obvious (or stupid) question, but when block sanding, do you actually use a block of wood? If not, what's the best tool to use, and what is the technique?

Also, the bed side to a '59 Apache has a tight radius convex contour in it...what's the best way to sand bondo/spot putty in that area?

Lastly, how can I tell when I'm "done"?

Thanks...

Chris

First I applaud and commend anyone that tackles a task that in most cases requires "learning" a skill. Body and paint are a learned skill that requires lots of hands on experience. If you search this site you'll find lots of info on this subject, most refer to books, and videos that are available. Keeping in mind that the end product will be determined by the skill you develope. I'm an old bodyman and I still block sand my work 3 times before I say its ready for paint. You might find someone that would be willing to coach you for a little incentive$

Truer words were never spoken. I always have farmed out body and paint work on my projects until my finances forced me to tackle this job myself. A couple of things I have learned that might help. There are no shortcuts, at least for novices like myself. If you want it to look perfect you have to follow every step the experts recommend- see the above post re: block sanding. The longboard is your friend. I purchased a couple of highly regarded DA sanders for doing the finishing work. I used one of them for 5 minutes. Even the fine finisher removes material faster than my skills can deal with it.

I cannot feel the kind or surface irregularities you describe that show up after painting. The surface may feel perfectly smooth but what a disappointment after painting. When I use a filler on a curved area I usually have to sneak up on the defect little by little. The block sanding will keep taking out the top of the defect until the sides are built up enough. A skilled body man can probably eyeball this to some extent and get to the final faster. Without more primer and a guide coat, repeat as often as necessary, I would never get the surface perfectly flat.

Finally, what helped me most doing body and paint work was to quit focusing on the goal (completing the job) and getting into the art of making the surface and paint as good as I could get it. This has turned out to be surprisingly rewarding to me despite many, many screwups and frustrations.

Chuck

The Eastwood Company has several sanding blocks you can purchase from them that are pro quality and also they have air sander long boards, DA's too. You can take a look at their website to see what you need for your job.
62Blue
Don

http://dura-block.com/durablockline.html
These are popular.

Heres a good place to ask body and paint questions.
http://autobodystore.com/forum/index.php?index

The block is stiffer than the palm of your hand and won't conform to irregularities.
Sanding with your hand just keeps amplifying the irregularities.

I used the Dura bloc long boards in two different lengths. The key is to approach the area from all different angles. Mostly at a diagonal and changing directions every so often. Use a guide coat and finish with some glaze type material (basically thinned out bondo) and you will be pleased. It takes lots of time, muscle, and patience to get it right.
This was my first attempt at bodywork and I am happy with the areas I gave sufficient attention to. Get lots of compliments, too.

I, too, salute you on taking on the task of body work and paint preparation.
Lots of work, but lots of satisfaction when you're ready for paint.

I recently did the entire body of a 1/2 ton panel. LOTS of LONG .. almost flat
surfaces. And, to add to the frustration the whole top half was to be BLACK.
This was clearly the hardest body repair/prep project I ever undertook.

Without 3 dura-blocks and an inline air sander, I would have gone nuts and crushed the thing!
It had lots of old CB antenna holes all over the sides, a long horizontal gash along
the rear belt line, and on and on...... The outdoor pics are two days after painting. The others are later as assembly continues in my shop....

http://gallery.me.com/squire001#100085

Go For It!
mike

I bought the Durablock kit and used it through my entire build. Basically, start with a long block and sand in long strokes past the damaged area. Spray more high build 2k, then mist it with dark primer. Sand again. Any dark areas means a low spot. Spray more 2k, mist with dark primer, sand again. Repeat until you no longer get low spots. Each step I would work up to finer sand paper grades. Usually, 220 for roughing, then 320, then 400.

Thanks to everyone for their replies. Looks like I'll have to buy a blocking kit and get to work.

At this point, I probably won't get to the bodywork until the winter. I'm starting to realize exactly how much work it is to do a paint job correctly...BUT, it's also the best way to add the most value to one of our vehicles.

I'm sure I'll chime in later when I actually get down to work.

Chris

These are all good pieces of advice. Sanding/prep for painting is the real key to fine paint job. Rushing through will leave you disappointed.
I tip I learned from my Dad I use regularly and find it as valuable as block/wet sanding.
Use the flat of your hadNd and run it over the area you are working. Y
If you concentrate you will feel valleys and ridges. You may have to sand more or apply a bit more body filler, whichever is appropriate. Then you block sand as a finite step. Another thing you can try is wearing a thin glove...vinyl etc. You will be surprised what thr glove allows you to feel that your bare hand may have "ignored".

Yep, a pair of Nitril gloves will actually increase your touch sensitivity AND not contaminate the surface.

Last year I bought a Dura Block kit. It came with (I think) 12 blocks for about $110. The longest is 18" and there are a few that are odd shapes, some are soft and flexible, others stiff, pretty nice blocks in my opinion. I wood recommend these too.

http://www.tcpglobal.com/s.nl/it.A/id.219800/.f#.V2COc_krKHs

They also make a 36 incher. There are several advantages to this system. One of them is the surface is stainless steel so you get perfect flatness. Another is they have rods going the long way through them so you can alter the stiffness. Very nice! The 36 incher is awesome for getting the back of the cab, roof, hood etc perfectly straight. Uses standard PSA sticky rolls.