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Why is POR-15 so frowned upon?

mitch_04
Learnin’
  • Aug 17, 2013
  • #1
  • shine
    Member
    • Aug 17, 2013
  • #2
  • mitch_04
    Learnin’
    • Aug 17, 2013
  • #3
  • mitch_04
    Learnin’
    • Aug 17, 2013
  • #4
  • Jim C
    Oldtimer
    • Aug 17, 2013
  • #5
  • ’68 Coronet R/T
    Oldtimer
    • Aug 17, 2013
  • #6
  • Bob Heine
    Oldtimer
    • Aug 17, 2013
  • #7
  • I am building a super-lightweight speedboat in my backyard. The hull is window screening that I’m spraying with Flex Seal. It doesn’t do a very good job sealing my gutters but I’m sure it will be perfect for my boat. Just busting your chops. My point is that POR-15 is mostly marketing hype. According to the flyer that comes with the “Super Starter Kit,” I should use it to repair cracks in the fiberglass on my Corvette.

    In a recent post on the Garage Journal, one of POR-15’s advocates shows how it bonded the lid to the can so tightly that the lid had to be destroyed to get it open. If your goal is to bond a paint can lid to the can, it’s the right product. Most of the guys who post on here are doing restoration work so they aren’t looking for shortcuts. Their worst nightmare is to spend a huge amount of time on a restoration and then have the customer come back six months to a year (or even longer) with bubbles in the otherwise flawless paintjob.

    Just think of the attributes of POR 15.
    – It adheres best to rusty metal. For best results you have to find a way to get the shiny metal on your part to rust. Seems kind of backwards.
    – Once cured, POR-15 is hard as a rock and about as flexible as plate glass. When applied to metal, the POR-15 expands and contracts at a different rate from the metal, so something has to give. The POR-15 still looks perfect but it has separated from the metal. You now have a rust manufacturing plant operating at maximum efficiency, completely out of sight under the POR-15.
    – Ordinary paint doesn’t stick well to POR-15. Once you’ve put it on, you need to apply a tie coat using one of POR’s primers.

    Best analogy I can think of is putting a waterproof, impermeable bandage over an infected cut. Looks good from the outside but who knows what’s going on underneath.

    Like most SPI users, I have made hockey pucks with leftover SPI epoxy. I have a couple that are years old and they still flex and bounce like they did at the end of their first week. Once you spray it on clean, prepped steel, it’s on there for good and it flexes with the metal. Make a hockey puck with POR-15 and it’s like a stone — no flex at all.

    I've noticed a lot of posts that are very against POR-15 and I'm curious why. I figured it would be a decent paint for frames/suspension components. I tried… ]]>