I just wanted to post a quick note on my experience with POR-15.
After my wreck in 2005 my dad and I put new battery s in my 1991 EZ-G0 golf cart.
The battery supports had gotten rusted and corroded.I repaired them the best I could and cleaned the metal best I could at that time with wire brush and water and backing soda and I brushed POR-15 on all the rusted metal parts.
Well the battery's served us well, as I just removed them yesterday and today I made some repairs.The por-15 had all peeled away and disappeared.
None had stayed in place.
Now,I have no idea why.It could very well be acid played a part.
But if you have a similar situation and thought about using this stuff,think twice,do some research because it sure failed me in this application.And the T chassis I brushed it on in 2007 that has hung in the shed since,has rust bubbles all over it.SO it didn't help there either.
Just wanted to share this experience to possibly save others troubles.
I've never tried the stuff, primarily because painting over rust strikes me as a particularly bad idea.
Don't know why you had trouble with the POR-15 but I have used it on quite a number of projects and never had a problem with it. I always use it to paint the inside bottom of car doors and find it works very well there. I used it on a 90 year old commercial threshold over 10 years ago that get a lot of traffic and it hasn't even worn through yet. My brother and I painted his lumber rack on his work truck with it then top coated it with a non POR product to give it some UV protection, that non POR product does show some scuffing but the POR has withstood all the abuse a builder gives their lumber rack.
You may be right maybe it was still some acid on the battery tray that gave you the problem. Don't know what could have gone wrong with your frame. Have you called the POR-15 people? I have found them to be very helpful.
Brushed it on an extremely rusty lawn tractor in 2003 and 10 years later that bubbly rust has yet to return. Couldn't ask much more from it.
I used it to paint the drive shaft roller bearing housing and touch up some missing paint on the rear axle case 2 years ago, and I haven't had any problems with it. You have to follow the instructions very carefully for it to work properly, I think.
Ive used it for years with no problems yet. My main use is door bottoms, rockers, ect. I like to pour it or "slop" it around and then blow it into the seams or cracks with a air hose. Just remember to cover up everything you do not want it on. including yourself. It does not come off after it dries.
Seems to be highly recommended. The only distinguishing factor in your case is (possibly) acid impregnated metal.
There are two absolutes in this world:
1. All coatings will fail in time.
2. There is no substitute for good prep.
I used it inside all the body panels on my rusty Coupe especially where they were against wood and moisture would stay. I like it. Also use it inside wheel rims. I scuff the loose stuff of and it seems to capsulize the rust like they say. If I'm still around when it fails I will report it here.
As Richard says >>> "I scuff the loose stuff off".
That's key to the process.......not just key......THE key.
I have used Eastwood's Rust Encapsulator for several years. It has worked great for me and while it doesn't require an overcoat it can be painted over.
Well this go around I used Duplicolor rust fix and a can of truck bed liner to coat the battery trays.
I put in Absorbent Glass Mat (AGM) batteries this time that are sealed so shouldnt be a repeat of the problem.
I put POR-15 on the running boards of my TT in 1999, and it's still there! Even the top of the "diamonds" has not worn through.
How well does POR-15 look when you paint with a brush? Does it look like it was brushed or will it flow out smooth? Depends on type of brush used?
It flows out remarkably! I remember at a car show several years ago there was a guy with a 1970 Dodge Challenger, his engine had the most perfect looking valve covers I had ever seen, when I asked him how he did them he said he painted them with POR-15 and a brush!
Dave H....yes, it flows well with a brush. I've used foam brushes successfully as well as those cheap "chipping brushes" on things like frames and axles, where a good smooth finish may not be quite so necessary. It works well. But then, so does good ol' fashioned DAR 9000 black acrylic enamel. Now that's a paint that REALLY flows out well. Can't hardly tell a good brush job from spraying. Finally found another can of it (for $88 a quart) after my 20 year old quart ran out. This stuff has an amazing shelf life, and super glossy.