Bilt-Hamber Deox Gel

[Citroënbender]

Got some moderately rusty floorpans (no perforation, but heavy flaking due to past spillages) that need treating on a job before underlay and carpet go back in.

Went to PPC and bought a bottle of the Bilt-Hamber "Deox Gel" (link to product and supplier, no affiliation).  I'm going to give this stuff a burl tomorrow. Have already prepared the areas to be treated by paint stripping and careful washing clean. Figure the gel can't make it worse, but not sure how much better it will end up. My point here is to show what it may do in "on car" applications.

Intend to complete the process with a POR-15 style overpaint, preferably in white, else silver.

[Citroënbender]

Initial results are very disappointing. I want to make it clear this commentary refers to the product as purchased in Australia, and it may differ to that sold elsewhere in the world. 

1. Viscosity is nowhere near the implied paste-like consistency.  It's a heavy free-flowing liquid, thinner than many methylene chloride paint strippers.  You certainly can't spread it up a vertical surface (as implied) in any meaningful thickness, nor let it sit reliably in the recommended thicknesses. of 2-3mm, it just slumps too much.

2. Coverage. In two words, total nonsense. One kilogram is stated to cover "up to" 2m².  On the bottle it says apply at 1-2mm coverage, in the online instructions 3mm.  Anyone who's put in rainwater tanks knows that 1mm of rain on a horizontal area of 1m² is one litre.  So if one applies 2mm/2m² that's 4 litres, and the stuff is definitely not lighter than water!

As would be apparent I am feeling a little frustrated by this, I am pretty much a "read the instructions first" person and it's impossible to diligently adhere to the guidelines.  I'll update in a couple of days when the cling film comes off and I clean up, but gut feeling is a flap wheel followed by phosphoric acid and a good rinse, would have been faster/better.


(Edited for grammatical accuracy!)

[Citroënbender]

A couple of photos, work still in progress.  Tomorrow (Wednesday) morning I'll be pulling the lunch wrap off, then scrubbing with wire brushes and grey scourers before thoroughly washing clean.

Evidently, something is happening, but how good it is - or isn't - is yet to be seen.

Behind the ball with this job, still waiting on connector set from "hg_garage" (Fleabay) and my mate is still repairing the seats.  Starting to worry about my deadline.

[Citroënbender]

First removal of the dressings, a good agitation with the wire brush and scraper, then LOTS of rinsing with a bucket of hot plain water and sacrificial Chux cloths (can't hose it, due to rest of car being in situ)! Used grey scourers to work the surface a bit as the top layer of muck came off.  I finished by using a flat scraper to free the flakes of rust it had not dissolved, but appreciably loosened, then vacuumed and damp wiped. Hot water is much better at removal of dried residue where the covering was insufficiently placed to prevent airflow.

I can say that it has done quite a bit of rust removal.  The smell is not unlike a chelating strip (cf molasses solution), very "irony".  There are no added perfumes it seems (some car chemical manufacturers feel they have to perfume things with the vilest scents which would even be disowned by a trough lolly).  It's also taken off the remaining paint which was softened but not removed by the stripper.

Is it a magic bullet as portrayed? Heck no - not even close.  I'm now at the point of indecision, whether I put on another coat or just go to flap wheels, a Scotchbrite disc and phosphoric acid. Glib remarks, helpful suggestions, opinions of all stripes and well-aimed peanuts all welcome.

[Citroënbender]

Well, I decided at first to use up the Deox Gel I had, by re-treating one side and seeing what changed. 

Not much...  This was after being left covered two and a half days, it was clearly still "wet" and therefore presumably active. Some areas are well-cleaned by the gel, others still have proud flakes of thick corrosion.

So, flap wheel time it is.  The key word remains; disappointment. I like things to work as promoted, I like to find comprehensive, cost-effective solutions, I like to share my findings good and bad because I'm not a knowledge hoarder.  If this thread saves someone else from being persuaded towards a quick fix that probably is neither quick, nor particularly cheap, that's a Good Thing. 

Flap wheel was applied, I used 120 grit and was cautious with flash heating due to the floorpans being both thin initially and then weakened by patches of deep pitting. Dust everybloomingwhere! Vacuumed, then washed; three ten litre buckets of warm water with a half teaspoon of CT-18 in each, and the surfaces around were "clean" again.  Kudos to Sydney's dry weather for aiding what I'm doing, but the agricultural drought is terrible. 



(Grammatical and content edit.)

[LaStregaNera]

You're way better off just buying a bottle of Phosphoric acid from Bunnings. Wire wheel the loose rust off, wash with phosphoric (or use a spray bottle on verticals to keep it wet for a while), don't let it dry, and wash once everything is a nice healthy mid grey.

[Citroënbender]

Well, well, well...

http://www.alfaclubvic.org.au/forum/index.php?topic=11113

Three applications and it's still not done. Mr Sanza has clearly more patience than I.

Re the phosphoric, I have Deoxidine 624 on the shelf, it's been a staple for 20+ years.  I think all that's in it besides dilute H₃PO₄ is a light surfactant to make sure it wets the material fully.

[LaStregaNera]

I wonder if it's a chelating agent like Molasses - would explain the glacial speed.

[Citroënbender]

Si, my thoughts are it's a blend of citric acid, molasses, maybe some buffers and an inert gelling agent. The way it clears deep pits is very much like a molasses strip but it doesn't flash rust once washed clean.

[Citroënbender]

Got to divert from this project for a few weeks with family matters, but an update of sorts.

The final application (total of two sessions offside, three nearside) scrubbed up yesterday, resulting in a measurably better outcome.  It also confirmed there was light perforation in a couple of places - bugger. Much of the corroded surface was appreciably clean, with dark speckling to the deeper pits only. Other areas where coverage had probably been too little, didn't come up so well. I may spot treat a couple of the worst areas with the small amount of leftover gel.

Biggest difference was my determined effort to break the "crust" of heavy corrosion with the P120 flap wheel.  A twist knot wire brush would have probably done as well or better, but they are often harder to hang on to!

As to whether I have received $120 worth of rust amelioration, I'm not sure.  Gut feeling is "No, it's overpriced" but my wallet may well be out of calibration.  Once I get pictures up, opinions are invited, as always.