Proper Procedure for Initial Blocking

R

RSchofield10

Promoted Users
I am underway with my first restoration (total beginner in the bodywork aspect, so please forgive me if this is common knowledge) and I have a question pertaining the first round of blocking. I have read the "Perfect Paint Job" and have spent several hours searching forums but I can not find a clear answer.

I have my firewall sprayed with 2 coats of epoxy and need to determine where filler is needed. Would the proper procedure be to lightly block the epoxy with 120 to find the low spots, then apply filler, block and seal with epoxy?

Additionally, the exterior of the car is in good shape and will need minimal body work. How does one determine during initial blocking if filler is needed for a low spot or if it could just be blocked out by moving to 2K primer, blocking and repeating as necessary?

Thanks in advance!
 
dhutton01 said:
Trying to fill lows with 2k can bite you due to shrinkage. Use a polyester primer or filler is my recommendation. I only use 2k to fill 180 or smaller sanding scratches.

You will get varying opinions on this but this is mine fwiw.

Don
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I am exactly the same way. Anymore I just 2K for a finishprimer or I use epoxy, any shaping is done with poly or actual filler. - I might add, this is on resto type work......shit I actually care about


daily driver stuff. Ill jsut shape the filler up to 180, 2k and go......
 
If the metal has been stripped, I start with 2 coats of unreduced epoxy primer. Let that sit at least 24 hours and then lightly block sand the surface with 120 grit. The sanded surfaces will appear dull and the low spots will be shiny.

The depth of the low spots will determine if more sanding will remove them or if filler is needed. Apply your filler well past the low spot so that it will feather into the epoxy.

For the existing paint you say is in good condition, you can do basically the same process except that it shouldn't need any filler. Regular 2k build primer should handle anything you find there.

If the panels have a lot of issues, that is where Polyester Primer, like Featherfill G2 or Slick Sand, come into play. They are like a spray on body filler that chemically hardens as opposed to the solvent flashing off as with regular 2k primers.
 
dhutton01 said:
Trying to fill lows with 2k can bite you due to shrinkage. Use a polyester primer or filler is my recommendation. I only use 2k to fill 180 or smaller sanding scratches.

You will get varying opinions on this but this is mine fwiw.

Don
Click to expand...
I agree also. Another advantage to the polyester primer (I'm using Slick Sand) is that it naturally provides a "guide coat" effect.
The sanded areas are a significantly different color than unsanded areas, so it is easy to see the lows.
And, I use black epoxy under the poly primer, so any highs show up easily as well.
 
I like to stay with epoxy for the first two rounds of primer at least. Excessive primer build can be avoided early by either fixing low spots in the metal by bumping or filling with poly putty. Neither bumping nor filling should be done after 2K is applied, and of the two, only filling can be done after poly primer is applied since bumping will crack it.

You don't want to be one of those guys that comes back and asks if filler can be applied over 2k urethane primer. Make sure the body is pretty straight before switching away from epoxy. Neither poly primer nor urethane primer is intended to fill dents, though poly primer can fill small dings if you really want it to.
 
Toolin said:
Agreed. Not a good place to find yourself in.
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crashtech said:
I like to stay with epoxy for the first two rounds of primer at least. Excessive primer build can be avoided early by either fixing low spots in the metal by bumping or filling with poly putty. Neither bumping nor filling should be done after 2K is applied, and of the two, only filling can be done after poly primer is applied since bumping will crack it.

You don't want to be one of those guys that comes back and asks if filler can be applied over 2k urethane primer. Make sure the body is pretty straight before switching away from epoxy. Neither poly primer nor urethane primer is intended to fill dents, though poly primer can fill small dings if you really want it to.
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I'm new to this but I certainly understand it needs to be straight before 2K urethane primer. Appreciate the advice.
 
Before I apply epoxy I go over the panel thoroughly with a flat hand to find any low spots or dings. You can use a body file or sanding block to reveal the edges of the low spot while you bump them out.

I try to get any and all bump work done before epoxy. Then over the epoxy I’ll do the finish work on the low spots with filler, then epoxy again and then block straight with 2k.

Pretty sure I’ve put filler over 2k before, that was probably 12 years ago. But the car hasn’t burst into a million pieces yet.

Now if I’m at 2k and find an OOPS! I use 2k glazing putty.
 
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