How to paint over Macropoxy 646

[steelekj6]

Hello!! I have a concrete foor that was originally coated with Maxropoxy 646 @ 15 years ago or so (give or take a few) and it looks as old as it is and then some!! I know the best way to go would be to use Macropoxy 646 over again, but that is not an option that is neither realistic nor desired at this point. I would like to use a waterbased epoxy this time around, but hear that not much will go over Macropoxy 646 and succeed at adhering to it (short of grinding).
I am curious if there is maybe a primer that could work to go over the top of a really old and worn out coating of Macropoxy 646 that will allow me to then apply a waterbased coating over that? Or is there some other form of prep i can do similiar (but not as extensive) to grinding? Etching will do NO good at all (i tried a few test spots). Will sanding with a really rough sandpaper possibly do a sufficient job??
Any and all tips or advice is appreciated. Thank you.

 

[Shea]

You just need to prep the surface like any other old coating that needs a recoat. Assuming the 646 is adhered well, degrease it and then rough up the surface with 120 grit sandpaper. Sweep/vac and then do a solvent wipe with denatured alcohol or equivalent. You are then ready to recoat. Just be aware that a water-based epoxy won't perform nearly as well.

 

[steelekj6]

Awesome!! So doing the whole grinding thing isn't the only way to make this work then??!!
And yes, i am aware that the waterbased stuff is not going to last as long, but this will make it so that the recoat process doesn't have to be a major ordeal which just keeps getting put off because there is never really an opportunity to do what needs to be done to do it right.... This will simplify the process and make it easier to maintain.
I appreciate your time!!

 

[Shea]

Awesome!! So doing the whole grinding thing isn't the only way to make this work then??!!
And yes, i am aware that the waterbased stuff is not going to last as long, but this will make it so that the recoat process doesn't have to be a major ordeal which just keeps getting put off because there is never really an opportunity to do what needs to be done to do it right.... This will simplify the process and make it easier to maintain.
I appreciate your time!!

That's correct. As long as the old coating is still adhered well you should not have issues.