Blocking primer.

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AdamR

AdamR

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I started blocking the quarters on my Dart today. My main concern is when to stop blocking, when to re prime with HI-Build Primer and when to make repairs with filler.

I have a few low spots I cant get out with just blocking because there are to close to stamping in the sheet metal like the gas filler and marker light. Those have high spots that make blocking the primer out impossible without hitting bare metal near the stamped sections.. Do I need to use a light coat of filler to even it out here ?

My other question is what grit should I be using ? I'm using 400 wet but the primer is real hard and cutting slow. Should I be using 220 instead ?

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hey adam,as a car restorer,paint and body man for a long time,i usually start with 180,dry on a long block,or air inline.its ok if you hot bare metal here and there,no sheetmetal is perfect from the factory,and after all these years its gonna be wavy.i guide coat everything before block sanding also,you know,fog some black on before you start sanding,even if its shiny paint to start with ,it will work.any low spots,dents,any imperfections,the black will still be in the low areas.guide coat is your friend,no matter what anybody tells you.get close with putty,guide coat on final blocking,then youll know for sure.same with sanding primer,between coats,water sanding,etc.and always,always,use a sanding block.thats the most important part of body prep.if its a round area,get a round block,if they dont make one the right shape,you make one the right shape.also on those light imperfections,use a good 2 part glasing putty,or sprayable fille,dupont has one,never use a one part glasing putty,they always shrink later when the sheet metal temp changes,then youll kick yourself after all that hard work.good luck,and have fun!
 
Thanks Toby. Theres guide coat on there, It just doesnt show well in the pictures.

If you look hard you can see the low spot below the gas filler were the body line disappears, Below the left end of the marker light and above the right end of the marker light near the body line.
 
Adam,When i am blocking primer and i am going to reprimer i use 180 or 220. When you can tell that everything is leveled out, that's a good time to stop blocking.This is where some good guide coat comes in handy.Your primer will fill small imperfections,but don't try to fill major problems with it.Get you some spray on guide coat or dry wipe on guide coat this will help you find your low places and scratches ,ext.If you get a high place and a low place together you will have to use some filler to fix that.Do your metal work first don't try to fill a dent or a place that needs metal work.As far as your blocking goes i would use a good primer,some guide coat,and 180-220 grit paper till i was done blocking and ready to water sand with 400-600.This is my opinion everyone does things different,but i do manage to make a living doing body and paint work.Also use urathane based material,not lacquers they will shrink.Like the other guy said use a good block that matches your contours.Also some masking tape on one side of your body lines will help you block to sharpen your lines.
 
Thanks guys, I'll pick up some 180 for the first round of blocking.
 
ive found over the years,be sure to work one area at a time.dont hink of the whole quarter,or door,etc,especially with a car like a dart or duster.the tape on the body lines works too,i been doing it so long,i block to the body line and dont go past it.the guide coat shows me when its straight.keep the block flat all the way to and dont let it rool past the body line,youll see if the lines straight or not.also,you tape areas you dont want putty to go,like that gas lid area,just before the putty gets hard,pull the tape off,and it will save you a lot of time.and yes,be sure you use all urethane primers,they dont shrink,or show scratches as long as the putty work is finish sanded with 180 or finer
 
One other item I didn't see mentioned, but perhaps you already knew or were planning for. After blocking it out (and I also use 180 dry) going back to fix whatever imperfections I find, it's another 2-3 coats of high build and blocking it out again - even a third time if necessary.

I stop blocking when a few bare spots start to appear or when I start seeing the spots I repaired just come through the haze.
C
 
I'll prime and block and fix till I know its straight. I was expecting to have to re prime most of the car anyways. Glad its got a vinyl roof !

I just order 6 Dura Blocks, that should help out.
 
Adam, i have a set of the dura blocks and they do work very well.They include a round block and several different lengths of flat blocks.For the long blocks you will have to get some 3m stick-it paper or similar.Like he says let the guide coat be your friend. good luck
 
tobysoldblue Has said it all. Start with 180, he has said it all, Im just starting blocking to at my new body shop job :D (i love the job) and no metal is perfect, heck i wonder how bad some of the brand new cars would be if you just started blocking a new car.

Looking good adam :thumbup: and yes glazing putty, we combind metal glaze and a form of spot putty which is really awesome to work with and really really easy to sand.

good luck
 
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