The Stovebolt Page Forums Home | FAQ | Forum | Swap Meet | Gallery | Tech Tips | Links | Events | Features | Search | Hoo-Ya Shop
Thank you for supporting those who support this site!
American Classic
Truck Parts

Fall is here

Hambone working on his Chevy

The last of the shows will soon be only digital pictures and fond memories. If you are getting your Bolt ready for some last cruises, or just thinking about putting her up for winter, be sure to check out what parts you need from American Classic Truck Parts. They still offer a 10% discount on parts in stock to Stovebolters. Please add your Stovebolt screen name and number in the comments at the end -- no special codes required.

Stovebolt On!

Stovebolt Site Search
Old Truck Calendars
2016 Calendars!
12 months of GMC Stovebolts

The calendars from last year are available for 2016. We will be starting from scratch soon. If you want one just like one from last year, you may want to check it out soon.

Check for details!

Who's Online
40 registered (5ptstar, 1953 panel, 3B, 68ironhead, 46gmcpu, 4 invisible), 144 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
37,658 Registered Members
48 Forums
99,593 Topics
763,201 Posts

Most users ever online: 509 @ Thu Nov 12 2015 04:34 PM
Today's Birthdays
53shorty, Chevy572, dads51, Eric J. Swindle, joeh20, John Moran, Mark Miller, OLDARMY95, Shiloh, weeds53, WilsoninLondon
Image Posting Policy
New Reply
Topic Options
#529277 - Thu Apr 16 2009 10:22 PM Phosphoric acid neutralizing
Dan B. Offline
Wrench Fetcher
Registered: Sat Mar 07 2009 08:08 PM
Posts: 72
Loc: Texas
I have been using phosphoric acid to treat most of the paintable surfaces on my 3100. Just ordered epoxy primer and am having second thoughts about shooting over the acid prepped metal. I read the whole thread about "phosphoric acid rules" but not much mentioned about whether it needs to be neutralized with anything before priming. This first step is obviously critical. Anyone with long term experience with this stuff?

#529296 - Thu Apr 16 2009 10:45 PM Re: Phosphoric acid neutralizing [Re: Dan B.]
red58 Offline
Registered: Sun Feb 03 2002 12:00 PM
Posts: 16141
Loc: north of the 49th
I haven't found it cause any problems, it's great metal prep for rust prevention, but also best practice when starting to shoot paint is to wipe down with a grease/wax remover immediately beforehand

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot
#529321 - Thu Apr 16 2009 11:44 PM Re: Phosphoric acid neutralizing [Re: red58]
Slickriffs Offline
Shop Shark
Registered: Tue Jan 02 2007 12:00 PM
Posts: 748
Loc: Fairfield CT
Yup-pretty standard series of events here-Never had a problem.

#529398 - Fri Apr 17 2009 09:09 AM Re: Phosphoric acid neutralizing [Re: Slickriffs]
Tiny Online
Registered: Sat Aug 06 2005 12:00 PM
Posts: 10043
Loc: South Central Kansas
If neutralizing it will make you feel better a simple baking soda/water solution will kill any residue.
Sweetie Before
Sweetie Now
Sweetie In Skirts
Dust: Mud with the juice squeezed out.
I was always taught to respect my elders, but it keeps getting harder to find one.
Don't bet on a horse named Tripod.
#529405 - Fri Apr 17 2009 09:35 AM Re: Phosphoric acid neutralizing [Re: Tiny]
sclor Offline
Wrench Fetcher
Registered: Mon Jan 08 2007 12:00 PM
Posts: 104
Loc: New Orleans
I use Ospho in a spray bottle, scuff with a scuff pad, then wipe with a paper towel. When I am ready to prime, I scuff with a scuff pad, then wipe with Wax and Grease remover. I have never had any problems.

The one caveat is that you can only apply phospohric acid once. Thus you have to be sure that the primer you are using doesn't also contain the acid. That means no etch primer and no hybrid epoxies that contain acid. I use Kirker Enduro that doesn't. I believe Valspar/House of Kolor is one that does contain acid. It is best to look at the manufacturers data sheets for the primer you are using to ensure that metal etched with phosphoric acid is a suitable substrate for the primer.

I hope this is helpful.
New Orleans
#529457 - Fri Apr 17 2009 02:19 PM Re: Phosphoric acid neutralizing [Re: sclor]
Spotbiltxo Offline
Shop Shark
Registered: Fri Jun 06 2008 11:34 PM
Posts: 805
Loc: San Antonio, Texas, USA
Steve makes a good point, but I wouldn't expect acid-acid reaction with a previously treated surface that is totally dry.
Once the phosphoric acid reacts with the rust to form oxide then the acid has been altered. Significant reaction would occur if the organic acids are viscueous.

As a note, it is always prudent to neutralize any surface treated with acid with fresh water. Most of the directions on a bottle of phosphoric acid reccomend this step in their directions section.

1950 Chevy 1/2 ton
1951 Chevy 1/2 ton
1941 Chevy coupe
#529507 - Fri Apr 17 2009 06:00 PM Re: Phosphoric acid neutralizing [Re: Spotbiltxo]
Jimmie D Offline
Shop Shark
Registered: Mon Feb 20 2006 12:00 PM
Posts: 542
Loc: Grand Junction, Colo.
Here is what Wikipedia had on the subject.
Rust removal
Phosphoric acid may be used by direct application to rusted iron, steel tools, or surfaces to convert iron(III) oxide (rust) to a water-soluble phosphate compound. It is usually available as a greenish liquid, suitable for dipping (acid bath), but is more generally used as a component in a gel, commonly called naval jelly. As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces. Care must be taken to avoid acid burns of the skin and especially the eyes, but the residue is easily diluted with water. When sufficiently diluted, it can even be nutritious to plant life, containing the essential nutrients phosphorus and iron. It is sometimes sold under other names, such as "rust remover" or "rust killer." It should not be directly introduced into surface water such as creeks or into drains, however. After treatment, the reddish-brown iron oxide will be converted to a black iron phosphate compound coating that may be scrubbed off. Multiple applications of phosphoric acid may be required to remove all rust. The resultant black compound can provide further corrosion resistance (such protection is somewhat provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes). After application and removal of rust using phosphoric acid compounds, the metal should be oiled (if to be used bare, as in a tool) or appropriately painted, by using a multiple coat process of primer, intermediate, and finish coats.

#530138 - Sun Apr 19 2009 07:22 PM Re: Phosphoric acid neutralizing [Re: Jimmie D]
50adrod Offline
Wrench Fetcher
Registered: Sun Dec 30 2007 10:13 PM
Posts: 196
Loc: Louisiana
I use SPI epoxy and they advise against it. they recomend sanded bare metal only. if you are using SPI epoxy just give Barry a call, he will help you out.
1950 custom streetrod build

71 corvette conv, 525 hp big block

Moderator:  Fourbrads 

Home | FAQ | Forum | Swap Meet | Gallery | Tech Tips | Links | Events | Features | Search | Hoo-Ya Shop