How To Block Sand Body Filler in Minutes

Hey, it’s Tony.  Thanks for watching the video.   This video is all about how to block sand body filler in minutes.  I’ve been getting a lot of questions about block sanding.

So in this Google Hangout video, I’m going to give you tips and show you how to do block sanding.

I have a car with couple of dents which I filled with bondo and sand it down with 80-grit sandpaper.  We have dents that are corned and some are flat ones.  For the big ones, we will use a DA Sander to cut it down and block it out.

Rasping is another thing you can do to reduce a lot of sanding time.  It’s like cheese grater rasping.  You have to rasp the body filler as close to the metal as possible.

Now, let’s talk about blocks.

The holy block has holes on one side and flat surface on the other.  I like to hold it where I can put my fingers in the holes.  It’s easier to use that way because it gives you a little bit of grip while blocking.

I wrap it with an 80-grit sandpaper disc and put some water into the holes so the water dribbles on the surface while I’m wet sanding.

There are longer blocks.  Some are eighteen inches, twenty-four inches and some are 2-foot long.  You use them for door panels and classic cars where there are a lot of flat areas.  You just need to put some straight sandpaper on it.

Now, we also have an air straight sander that you use on flat areas.  I usually put an 80-grit or a 36-grit sandpaper.  You need to put a heavy duty sandpaper on it.

I also have a Dura-Block that you can use on curves.  It’s rubbery and you can roll up your sandpaper around it.  It’s especially good on classic cars where there are curvy areas, especially around the lights.

Then, you also have a foamy block which is good for water sanding and cutting things down quickly.  These are also good for corners.  I got mine from Meguiar’s.

You can also use a basic painter stick for tiny areas.  Just break the stirrer and wrap a sandpaper around it.  I use it in-between doors and between fenders to correct gaping.

You can also use these old school rubber blocks.  You can use anything as a block. Let your imagination run wild.

When you sand an area, you have to do crisscross sanding and follow the body line.  The goal is to feather out the edges.

If you want to make sure that all the dents are taken out, use a regular rattle can, black paint to check.  Spray the guide coat and let it dry.  The dark areas are the low spots.

I usually keep a box of used sandpapers with all kinds of grit.  I only throw sandpaper away if they’re really bad, but if there’s a little bit of grit left on it, I keep it in this box for later use.

Make sure to constantly hit your sandpaper pad to take all the dust off.

Once you get the general shape done and you don’t feel any dent, get a 240-grit or 280-grit sandpaper and scuff the area then prime it.

You have to make sure to sand the whole area so your primer is going to blend into it.

Once your primer dries, you can go ahead and wet sand it with 400-grit sandpaper.  If your primer didn’t take care of the pin holes and deep scratches in your bondo, fill it with a little bit of glaze putty.

Your primer should take care of little ripples when you block sand it.

You can use from 240-grit to 320-grit sandpaper to scuff and smoothen the bondo.  It doesn’t really matter as long as you get it a little finer before you prime it.

That’s how you would block sand easily by hand.  If you know how to use a DA sander, use it. It’s a lot quicker and comes in really handy.

I would use a DA sander on all of these block spots.  I have an 80-grit sandpaper on my regular DA sander to take these down.

Keep your DA sander flat on the surface and hold it nice and flat to cut the high spots.  Always follow the body line so you won’t screw up.

If you have a thick piece of bondo, use the tip of your DA sander to push against it.

You keep them flat on small dents and it’s easily filled.  That’s how quick a DA sander can take down your body work.

Sometimes, you want to cut the high ones down and finish off with a block sander if you don’t feel comfortable using a DA sander.  Put some guide coat and finish it off with a block.

If you feel comfortable with the DA sander, finish it off then hit it with a 280-grit sandpaper, then prime it and you’re done.

When working with door handles, you want to tape it or mask it up. If you’re really anal-retentive, you can take the door handle out.

I’m going to block the area around the door handle and probably hit it with tip of the DA sander to cut it down and finish it off with a block sander.

These are the basics.  I hope you liked it.  I’m going to have the rest of the videos available for you within the LearnAutoBodyAndPaint VIP course.

Please Subscribe, Like, Share and Comment below the video.

Go to LearnAutoBodyAndPaint and get your FREE 85-Page Auto Body DIY Manual.  Do your own DIY auto body a success.  Go ahead and tackle your car now.

Talk soon!  Cheers!


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