# Dinitrol 3125 and POR 15



## MK1Campaign (Mar 27, 2007)

Has anyone used either of these?
I am thinking of using them on a car that's previously had the rear quarter replaced. Dinitrol in the panel cavity and the POR behind the wheel arch edge.


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## jubileebug (Jan 25, 2008)

My restored beetle had the floor pan painted inside and out in por15. Quality stuff IMO


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## NornIron (May 12, 2007)

Use 3125 on a number of my toys, and also some of the POR15 range in the past. What product are you considering for the arch lip...?


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## Steampunk (Aug 11, 2011)

POR-15 is an American MCU (Moisture Cured Urethane) coating; it's a decent product, but one must be cognoscente of its application. POR-15's bond with the substrate is purely mechanical, so you must have a 2-mil (50-micron) RZ surface profile to allow it to key into; this can either be created by abrasive blasting, or by solid preexisting corrosion (Though the former is obviously vastly preferable regarding longevity.). Apply it correctly and you are looking at circa 1500+ hours of rock-hard salt spray protection; apply it incorrectly and it will peel off in sheets, trapping moisture and accelerating the corrosion process if not immediately repaired. It also cannot be directly painted over, and needs U-Pol Acid #8 as an intermediary primer to allow top-coats to bond. 

To be honest you as a UK resident have much better anti-corrosion products than we do in the United States, and something like Bilt-Hamber Electrox or Epoxy Mastic would be much more forgiving - if not even more effective - options in the long run. If you are still interested in MCU coatings, I would instead look at POR-15's cousin, KBS Rustseal. It is not as overpriced as the original, and many say it is slightly easier to work with.

Regarding Dinitrol 3125 I have no personal experience, though I do know that its salt spray resistance is a little low in comparison to its more recent competitors (Only 480 hours ASTM-B117 off the top of my head.), and it trailed in performance during the Practical Classics 3-year corrosion test. Bilt-Hamber Dynax-S50, Noxudol 700, and Mike Sander's Korrosionschutzfett were at the top of the pack at the end of the test. 

Hopefully this helps... Corrosion protection and repair is my specialist subject, so if you need any assistance just let me know.

Steampunk


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