View Full Version : OT: Rust help?

Cecil Walker
07-31-2006, 09:57 AM
My wife has a 20' X 42' greenhouse with a galvanized frame. One of the horizontal angle plates is rusting! These horizontal plates rest on top of a 2' tall brick knee wall, and all the vertical supports rest on this angle plate. There are 4 plates per side, however only one is rusting. I do not want to replace if at all possible....major job. This is in an area that gets daily water from a misting system. I've thought about cleaning and spraying with cold galvanize or POR but......... is there a better solution? I'm looking for help on this one. Any suggestions? Thanks.

07-31-2006, 11:42 AM
I've had good luck with Rustoleum's 7400 system. http://www.rustoleum.com/product.asp?frm_product_id=220&SBL=2

J Tiers
07-31-2006, 12:53 PM
Well, you are going to HAVE to replace it...... after you pull it, clean it, paint it, you'll have to put it back.

If you just paint it in place, the rust underneath it will still be in progress...

Galvanizing is all very well....... but it has a lifetime. When the zinc is gone, rust will appear anywhere the remaining zinc is too far from.

The zinc must be part of the same electrochemical "cell" in order to work, so if it is too far away, it can be inactive for a particular area. Might be because the electrolyte (pooled water) does not touch both the steel and zinc, or because local action "shorts" the cell.

The zinc goes fast for electrogalvanizing, and slower for hot dip (due to coating thickness). But it goes, eventually.

07-31-2006, 01:16 PM
If it is not too far gone JT's suggestion combined with Tinkerer's makes sense. If it is still structurally intact, wire brushing off the loose rust, an electrolytic rust removal bath (google on rust removal) with a battery charger and followup passivation with a phosphate treatment of the derusted metal followed by the Rustoleum ought to take care of it for a decade or so. I built some greenhouse benches in '80 and used expanded mesh that I covered with a predecessor to the Rustoleum primer, and it has remained intact and rust free since. Not as wet as yours but sprayed periodically over 26 yrs.

Cecil Walker
07-31-2006, 04:17 PM
Steve, Tinkerer: the 10' piece in question is structurally sound. I think a combination repair is in order for the short term, then wait and see if the others start rusting.

J Tiers: Yep, you are correct, i know it will have to be replaced at some point in time, and it will be a major job, but this will buy me time. Major repairs have to be scheduled for spring or fall because of the heating and cooling requirements. She's got 2000 orchids in that greenhouse and if anything adverse happens.......well......it won't be a pretty sight and i don't want to be there.

Thanks for the advice.

Bill Pace
07-31-2006, 04:24 PM
2000 Orchids----!!!! WOW!

Thats probably where your Gatling gun and the Brownings stay, -----guarding those treasures!

07-31-2006, 06:16 PM
Try this



07-31-2006, 06:40 PM
Go to a plumbing supply store and purchase a couple of magnesium anodes for water heater (~$40@). Clean off the rusty angle plate and bolt the magnesium rods to it ensuring close mechanical contact for entire length. This should give you sufficient protection until you can do a proper maintenance on the structure.

08-01-2006, 01:37 AM
there is a car product that you can find at almost any car store that is like a paint/paste that you can put over rust and it will stick, and thus preventing the rust to develop further, I dont know what its called but its out there! sorry i cant be of any more help

EDIT: took me 2 seconds to find it! here u go http://www.interstateproducts.com/1stepinfo.htm

EDIT (again): found another one for you! http://www.magnetpaints.com/underbody.asp

08-01-2006, 08:36 AM
Used a rust converter paint on the battery tray of an old pickup, it still looked good 4 years later when I gave it away.

A.K. Boomer
08-01-2006, 08:48 AM
thats the ticket i would try, there are a bunch of different manu. ,,, hyde products makes one and what it does is convert rust into primer that you can paint right over,,, dont know how deep in it penitrates, do know its not just surface stuff though...

08-01-2006, 09:10 AM
Rustroy is the product that I use when needed. there are any number of similar products out there that perform the same action. that is to convert rust to magnetite and seal the area.
Another option that I swear works is Chesterton pure nickel base anti seize compound made in the good old U.S.A . It will not wash out but be warned it can get everywhere:D . product # 82359

P.S. I should have stated that Chesterton will not neutralise the rust in any way. However, as a barrier, it will prevent any further corrosion taking place.

Cecil Walker
08-01-2006, 03:58 PM
Thanks for all the help, i really appreciate the response. Guess i know what i will be doing Saturday now.

J Tiers
08-01-2006, 09:46 PM
That "rust reformer" (one of the brands) does work, but you HAVE to paint over it. It isn't a paint itself, and won't hold up to weather.

I don't know how it works with zinc. Some materials don't like to stick to zinc, and some are adversely affected... It might "poison" the rust conversion. Or not... You might try a spot first, and see, before investing heavily in doing it.

My original reference was to the fact that you'd have to take it out to clean and paint it on the bottom, so no matter what, if you wanted it to last, you'd be removong and replacing it......