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Block sanding ?

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78elk
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Block sanding ?

Post by 78elk » Fri Jul 31, 2015 6:09 pm

I am block sanding the Elk and have a question. I see high and low areas where the difference appears to be a few layers of paint. What is the proper way to make the panel level?

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Re: Block sanding ?

Post by 78elk » Sun Aug 02, 2015 3:41 pm

This is my first time at doing this. Do I need to spread a paste on the lower areas or will more coats of the Buff primer I plan to use. I plan to paint it with JD Blitz Black using the JD Buff primer.

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Re: Block sanding ?

Post by melloelky » Sun Aug 02, 2015 4:15 pm

by blocking the layers of old paint you're essentially knocking the higher points down that does aid in the leveling process.this is when the lower areas come to light.realistically skimming the lower areas with filler or a putty (depending on how low it is)is the way to go rather than putting your primer on oh so thick with the idea that it'll be enough build to make the panel straight.yes blocking the primer does level the repair area but relying on the primer alone isn't as good as it sounds.it also brings the repair area to the same level as the excising paint which is what you're going for.how long of a block are you using? if you're using those short four inch rubber ones from the part store,you might want to consider using something a little longer. also are you sanding in a straight line with your block or are you making a diagonal 45 degree kinda stroke?using a longer block and going in a diagonal motion are a big help when blocking a car.
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Ribbedroof
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Re: Block sanding ?

Post by Ribbedroof » Sun Aug 02, 2015 4:26 pm

It's hard to answer without seeing it in person. Primer/surfacer will fill low spots if they're not very deep, but you really want to limit how much film build is on the car. The major paint mfrs recommend no more than 12 mils, but I know in the real world cars get more than that, especially in collision work where the same panel may be repaired/painted several times.

One trick you can try is to use some wax/grease remover and mist an even coat of it on the panel. You should be able to see how flat it looks in the reflective light.

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Re: Block sanding ?

Post by Ribbedroof » Sun Aug 02, 2015 4:30 pm

To add to the block discussion, my personal preference is Durablocks. Not horribly spendy, and work well.

Also, I have noticed that some people use way too much pressure...you really want to let the block do the work.

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Re: Block sanding ?

Post by 78elk » Sun Aug 02, 2015 5:04 pm

Thanks for the help. I currently use durablock blocks. I can't feel the die between the high and low areas. If I were to feel them I would add filler. I have a new after market door that very wavy. With a straight edge, I CA see gaps with around 1/16 of an inch of light showing through in places. I have tried some puttyI but I either getting it to thick or not getting the hardner in the right amounts. am willing to look at all ideas.

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Re: Block sanding ?

Post by melloelky » Sun Aug 02, 2015 7:26 pm

dura blocks are nice blocks,they're better than the hard rubber ones i started out with.i wouldn't be too concerned with a 1/16th of an inch,for what you're doing the primer will take care with that.when i started out i had the same problem telling the difference,sometimes running my hand over the sanded layers of paint was confusing too i thought it was high or low.if you think somethings low,block it in one direction,if its low the scratches will only be on the high spots around it.a kid i worked with used to run a paper towel over it with his hand flat on top of it.he said it helped.telling the difference between high and low is something that comes with time doing bodywork.have you used a guide coat before?
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Re: Block sanding ?

Post by 78elk » Sun Aug 02, 2015 7:40 pm

Thanks for the help. I tried the guide coat a little on the hood. It sanded off on high areas and didn't on the low ones. I have been using clean shop rags and nitrile gloves to find low areas.

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Re: Block sanding ?

Post by melloelky » Sun Aug 02, 2015 7:55 pm

oh cool,when using it on a larger area that's when it really shines.like if you primed an entire panel then used the guide coat it would show up really well.sounds like you're on your way.
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Ribbedroof
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Re: Block sanding ?

Post by Ribbedroof » Sun Aug 02, 2015 8:02 pm

We had a guy that always used a cotton shop towel, said that was the way he learned it back in the 60s

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Re: Block sanding ?

Post by 1981Regal » Sun Aug 02, 2015 9:59 pm

my suggestion is to put your hand in a plastic grocery bag kind of like a glove. Feel the panel section like that, it makes a difference.
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78elk
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Re: Block sanding ?

Post by 78elk » Sun Aug 02, 2015 11:29 pm

Thanks, I'll give that a try.

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