Epoxy over rust pits... How much is too much???

[JoeMan]

I know you can seal up small amounts of rust in the bottom of a pit and it will cease to grow... Still there, just inactive as I understand it... The pics are of a 1928 Pontiac hood... I used a product called PHIX on half... cleans the metal nice, dissolves rust similar to Naval Jelly... works a little quicker from what I've found... Leaves a zinc phosphate coating that I then 80grit and 3 coats of epoxy before body work... Anywho, what do you guys think as far as the rust that is left... very stubborn at this point... you can see what the other half looks like before the PHIX... just one treatment on the clean half, with a little bit of wire wheeling on heavier areas... did a '67 stang roof that was horrible and it eventually cleaned to rust free metal (nevermind the 25+ hrs of soaking, wire wheeling, and picking)... And a side note type of question... How much does epoxy shrink from what you've found... I have a puck from a bottom of a cup thats like 3-4 mnths old... still a little rubbery, and didn't shrink to the point of cracking or anything... probly an 1 1/2thick puck too...

 

['68 Coronet R/T]

I would media blast that panel to remove the remainder of the rust.
Here's one that looked like brown spots after stripping and sanding:

Same panel after blasting and DA with 80 grit:

 

[Barry]

[QUOTE='68 Coronet R/T;17580]I would media blast that panel to remove the remainder of the rust.
Here's one that looked like brown spots after stripping and sanding:

Same panel after blasting and DA with 80 grit:

[/QUOTE]

Perfect and so easy and there are no sleepless nights after painted.

Sorry but the other stuff is not cleaning the metal like it should be and if you ever look at that scale rust left in the Pitts under a microscope, there is a lot of places for that stuff to hide and expand down the road to cause a gas after the car is painted.