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Fri Mar 20, 2015 7:23 pm

I've welded on a three panel rear trunk-floor support (called an inner valance) that runs around the perimeter of the rear of my car on three sides - it connects the trunk floor to the lowest edge of the quarter panels and rear panel of the car. It creates a large "U" shaped cavity around the rear of the car behind the wheels. Think up-side-down bull horn for it's profile or a funnel with no hole for drainage. Obviously a rust trap waiting to happen.

The inside and outside of these panels were well cleaned and painted before welding in (6+ mos ago) - except for the linear strips of metal that I left exposed for welding (I had weldable primer that refused to spray - Sem's brand = do not purchase!).

The car's sat outside during this wet winter and I need to treat the (bottom of) the inside of this cavity. There is a gap around the perimeter of the trunk floor of about 3/4" inch that I can spray (or pour) some protection all around the outer three sides of the trunk. I have purchased a can of eastwood's "Internal Frame Coating" w/ the long flexible hosed, multi-spay nozzle. Is this what you guys would use for this? My other thought was to get some Por-15 and pour it around the edge, to let it pile up at the bottom. But, I would not be able to clean and treat before top coating with the Por15 - so i don't think that it would be effective, right?

Then this got me thinking... how does the 'Internal Frame Coating' work without having to mechanically remove rust and treat the area (w/ Metal Ready or whatever) before adding the top coating (like w/ Por-15)? Could the 'Internal Frame Coating' even be effective... then if so, why not use it everywhere else you'd use the other? Thought?

Doug C

Sat Mar 21, 2015 6:25 pm

..ok well, what about pouring or spraying a Phosporic acid mix (1:3 w/ water as recommended for paint prep) down into the crevice, then Internal Frame Coat after it's all dries up?

What happens to Phosphoric acid if it's not washed away (because i would not be able to)? I hear sometimes that it works as a primer.. but maybe that's only if it's washed away - IDK. Perhaps the IFC wouldn't stick to a phospho washed panel that has thoroughly dried?

How about, as an extra precaution.. spraying a waxoyl coating over the dried Internal Frame Coating (whether over phospho or not) - any reason that wouldn't work at staving off any rust that's trapped under the Internal Frame Coating?

I'm just trying to be thorough as I do not want to go thru replacing panels again later. I have seen (in another thread) a test panel that was sprayed with Internal Frame Coating and left outside for a year... it looked pretty good for what it went thru but rust seemed to be starting to peak thru the surface in some areas.

Doug C

Fri Jun 26, 2015 8:02 am

I'm looking at just the same thing (tho areas on my split bus - rockers, outriggers, frame rails, etc)... surprised so one chimed in on this thread.
Doug - What did you end up doing?
I was thinking of spraying POR into the cavities with Eastwood's undercoat gun...

Fri Jun 26, 2015 8:14 am

I believe a waxoyl spray would be the most effective. It will flow into seams, absorb into existing rust, and won't peel or flake off. Oily metal simply doesn't rust.

Fri Jun 26, 2015 1:04 pm

Back in that area I was working on (under trunk support valance) I rinsed in a phos. acid mix then rinsed w/ fresh water after a while BECAUSE there is drain holes at the corners that were free and clear. Then after all had dried I used eastwood's internal frame coating aerosol.

I don't think you can be too cautious though.. and the waxol after the internal frame coating (which is basically a paint type of material) might be a good idea IMHO.

One note on the internal frame coating and it's long flexible tube - you either need to be ready to use the whole can OR risk wasting the ability to use the tube a second time (but it can be removed). Maybe it's meant to be cleaned with a solvent after each use - but I don't remember reading it on the can though. When I tried using the can after sever days of sitting it was seriously clogged.. then after trying to spray the stuff and nothing coming out, I removed the nozzle for cleaning and it basically exploded stored up pressurized paint all over me upon removal (LOL)!

Doug C

Mon Jun 29, 2015 10:46 pm

Step One: remove rust.

POR15 doesn't really do that that well. So Phosphoric Acid is what you need. Let it sit for a while, then rinse it out (water is fine, but you don't want to let it sit)

Then use the internal frame coating.

Then use something like Waxoyl to make sure any water that does get in there is repelled.

Aaaannd... done

Tue Jun 30, 2015 7:07 am

Well, I'm talking about after welding on new outriggers, rockers, etc.
I've tried some of eastwood's products and have not been terribly happy with them... I've used the rust encapsulator (after cleaning, and eastwood's rust converter), and found it didn't hold up nearly as well as the POR.

Tue Jul 07, 2015 11:06 pm

Yeah, their Rust Encapsulator isn't that great. It's not bad or anything but POR is better (but then I consider POR one of the worst anyhow - master series all the way).

But their other stuff is good. When it comes to PAINTS they are good.

Sat Jul 18, 2015 7:40 am

abritinthebay wrote: Step One: remove rust.

POR15 doesn't really do that that well. So Phosphoric Acid is what you need. Let it sit for a while, then rinse it out (water is fine, but you don't want to let it sit)

Then use the internal frame coating.

Then use something like Waxoyl to make sure any water that does get in there is repelled.

Aaaannd... done

NO.....you do NOT rinse out phosphoric acid mixture. Read the instructions carefully. There is a reason you dont wash it out.

The phosphoric acid MUST be in, contact, until it, fully, dries. This is a chemical reaction....not a coating. The chemical reaction completes on the change of state from liquid to solid.

If you ard worried about the powdery residue.....then dilute the phosphoric acid mixture as per instructions....and use at least two applications.

The Ospho brand product does not eo as well with dilution. I have found that Jasco prep and prime has about 2.5X the solution strength of, Ospho. It does better with proper dilution.

If observe any excessive powder residue. ...its because the rust was, very deep in that spot.

Only when its, been dry for at, least 24, hours....can, you wash the surfaces....preferably, with a fast drying solvent. If you must use water.....you need to let it dry for at least two, days with air blowing over it or the humidity in the surface will defeat the ability of the converted metal to be an effective primer for binding coatings to. Ray