Rusted steel after clear coat!! HELP!!

[dustywill]

Okay,
I have been through the evolution here in the last 6 months of clear coats. (I've only been doing this that long) I first started with a lacquer rattle can and that finished pretty well, but they changed the nozzle and it was an arm and a leg. I also saw that the metal would later rust even after several coats were applied. I blamed that on the nozzle change and maybe thin coats. Now I have moved to a shopline clear coat that seems to be pretty good, but I still have been getting rusted metal under the clear. It seems to continue to get worse even after the part is sealed. This has become a quality control issue for me and need any help I can from you guys. It is hard enough to make money in this without killing my self reworking and refinishing all my polished steel.

Here is my process. I cut, acid bath in muriatic acid, wash off with water, grind to a polish with 120 grit flap disc. Then hang in the paint room until I have a batch (later the same evening) to clear coat. Then I mix the clear and spray. I usually put at least 2 maybe 3 coats of clear on everything. I shoot from angles to get inside the cut outs.

Any suggestions? Here are some pictures of what I'm seeing just 12 hours after coating.

2013-09-07 13.36.59 (Medium).jpg

2013-09-07 13.36.43 (Medium).jpg

2013-09-07 13.36.16 (Medium).jpg

2013-09-07 13.36.07 (Medium).jpg

Thanks for any help,
Byron Williams

[elvenhome21]

I have the same issue when I do acid bath. I can let the parts soak in baking soda for a couple mins. Wipe dry and spray paint within a couple mins, And I still get rust coming up through the paint. I think it has something to do with the acid still being active and eating away at the material without being fully neutralized.

[abmetal]

I quit using muriatic acid for that reason. After soaking in muriatic acid, I'd soak it in baking soda/water solution, then use a scrub brush on it while in the solution and then rinse. I'd still get rust. So that's why I quit using it even though I still think our high humidity is partly to blame.

Allen

[elvenhome21]

Im almost wondering if a person has to soak the steel in like a draino/lye solution to completely neutralize the acid, or if you have to sandblast the parts or use an etching primer to stop the rust.

Im leaning towards the etching primer for right now, but until i figure out something that works im not using the acid except for tiny parts i cant grind.

[dustywill]

It hasn't rained here in a few weeks, but we do have the high humidity. I have not yet installed my air dryer either, so my air is a bit damp, but my big question is how it continues even under the clear. My air dryer should go in next week.

[steelfx]

WIDTH-REPLY.jpg

I have a pretty good idea what's happening, but would like to know the approx. measurement of one area.

It's not the Muriatic Acid, guys...

Bill

[dustywill]

Bill,
I'm open to any theories. That measurement is about 1" wide. The rust area shown there is about 1/8 in. wide.
Thanks for joining us,
Byron

[steelfx]

Bill,
I'm open to any theories. That measurement is about 1" wide. The rust area shown there is about 1/8 in. wide.
Thanks for joining us,
Byron

My take is entirely subjective, without actually seeing the piece in person, so please don't take any offense.
I suspect that the little bit of rust showing was there prior to clear-coating. Grinding/polishing near the edge
always seems to miss a little rust & it's hard to see unless you're working under a very bright light.

In fact, the prismatic effect of grinding & polishing takes on different looks from different angles of lighting.

Clear-coating accentuates any nuance in the striations of grinding/polishing, as well as subtleties in the patina
or dyed metal, that you just can't see until the clear is on.

The only way that rust can form under a properly applied clear-coat is in the presence of water & oxygen. Flash rust,
under close inspection, nearly always starts out green, then as it oxidizes, turns to the familiar red (iron oxide).

If rust were to form under a solvent based clear-coat like ShopLine, which is a PPG product, it would actually cause
delamination or blistering in that area & would be the result of latent moisture. ShopLine is a great product to use over an opaque base-coat, but is slightly amber in color compared to DELTRON, which is very, very clear.

In this case, I'm relatively confident that the minute amount of rust was actually already there, just very hard to see.
I call those imperfections "character" and charge extra.

Or, due to high humidity, it may have formed between the time you polished & clear-coated. If that happens & it's still in the flash rust stage, you can wipe it off with a lint-free tack rag. I live in the desert SW (southern Utah) where high humidity is rare.

Also, Muriatic Acid is a household, common name for Hydrochloric acid. It's actually a gas infused into water, hence the 31.45% dilution rate that is common with Muriatic Acid. Once a piece of HR is removed from my acid tank, I rinse & neutralize with plain water. I've never used a base rinse, e.g. Baking Soda (sodium bicarbonate) or any other alkaline
rinse after the acid bath. It's totally unnecessary. Once the gas molecule bearing liquid (muriatic acid) is rinsed, there is no longer any acid on the steel. None.

The neutralizing liquid (OFF-X?) I make is more geared to the other types of acid in the patinas & I only use it when I'm patinating both sides of a piece, to prevent moving residual patina from one side to the other. And, it contains wetting agents & surfactants, along with a base.

There are very, very small amounts of any type of acid in my patinas. Some of them have none. Some have more than one type.

Hope that helps.

thanks,

Bill

[dustywill]

Bill,
Would it be uncommon for this rust to continue to grow then? I have many pieces that have been around a while and have noticed rust that was not there when the piece was finished. I even had a return from Florida that had grown rust in several places.

I only use water for the rinse as you suggest. I will continue to fight the good fight and be more observant with my grinding.

Thanks for your help,
Byron

[steelfx]

Bill,
Would it be uncommon for this rust to continue to grow then? I have many pieces that have been around a while and have noticed rust that was not there when the piece was finished. I even had a return from Florida that had grown rust in several places.

I only use water for the rinse as you suggest. I will continue to fight the good fight and be more observant with my grinding.

Thanks for your help,
Byron

Not uncommon at all. Once rust gets a start, it has a way of continuing. As you probably know, the edges of our pieces are the most vulnerable. Film thickness of spray clear or PC clear is thinner on the edges & the right-angle corner of
'flat to upright'. I try to get a 1.8 mil (or greater) film thickness, but on edges that's virtually impossible without using a detail gun or air-brush. Which I don't recommend simply because it's too time-consuming.

It's just one of the little battles we have in steel finishing. Y'all that live where it's really humid have it even worse.

Note: Flash rust is powdery, easy to remove with a tack rag, BUT, if present, it acts like a 'release agent' and air pocket under the clear, thus creating the potential of delamination. One trick you might try is a couple of light coats of BULLDOG? adhesion promoter. It's available in rattle-can, qts. & gallons. It preps the steel (or any other substrate) for a more solid bond between the steel & top-coat/s. It's imperative though, to shoot your clear within 7-10 minutes after your application of adhesion promoter.

thanks,

Bill

[AIRFLOWKID]

Bill,

Again very informative! Just another reason I buy my finish products from you.

Thanks again,

Tim, Red Robin Creatives

[rustyhook]

I am having this same issue so I logged on to the board and found this post. thought I'd give my 2 cents and ask one question...

my 2 cents:
take the acid out of the equation. I am using cold rolled A-36 carbon steel. I cut, and grind with 36 grit then 120 grit paddle wheel disc to an awesome smooth finish. I use air to blow off piece then wipe with clean micron rag. Then I clear coat, usually 2 to 3 coats of Shopline Automotive Clear. I am getting the SAME results as pictures shown previous. I believe Bill is right in the fact that the rust is starting from the edges. See pictures below. I believe too that the rust pictures posted most likely were not 110 % sanded before clear coat thus causing the issue.

one question:
should I be using some type of solvent cleaning before clear coating to clean material more. If so, what?

RH


PIC 1..... entire piece I have with rust issue so you can visualize size. approx. 45 long x 25 tall
PIC 2..... is up close of the rust. you can see it appears to be starting at edges and then growing

Wahoo1[1].jpg

Wahoo2[1].jpg

[Sampson Jones]

Bill is correct .Many times I thought I had a piece mirror finished only to take it in another room under different lighting and see some rust . Move your piece in different angles under a really good light . Wipe your piece down with a tak rag . Clear with minutes of your final sanding .
[quote][/quote]

[dustywill]

Bill is correct .Many times I thought I had a piece mirror finished only to take it in another room under different lighting and see some rust . Move your piece in different angles under a really good light . Wipe your piece down with a tak rag . Clear with minutes of your final sanding .

This is exactly what I have decided as well. I am getting better at it. In some cases it turns out not to be rusted, just not fully ground. I have since moved to P&O steel for nearly the same price and it has enhanced my works flow and start to finish time. I have yet to perfect things, but the change in light helps a ton. I need better eyes.

[ColoradoWayne]

Great conversation. I've had a lot of the same issue, clearly I need much better lighting. I switched to CR too, just a lot simpler for me. Thanks to all for sharing.

[yeomansjon]

I am having this same exact issue. I notice it mostly on bare metal with clear coat finishes, not so much with SteelFX patinas though. I more or less discovered the same issue Bill mentions in that the rust is flashing between the time I grind to when I clear. So having just discovered this I have been fully grinding (120 grit flapdisk) every micro inch of surface obsessively and immediately clear coating (less than 5 minutes later). Time will tell how well this work. I'm using 11ga CRCQ carbon steel sheet. For the amount of time I spend grinding i'm wondering if i'm better off using aluminum or stainless.

[Capstone]

Although I don't have long term results yet, one method I'm using to try an combat future rust issues is to grind the backside of the piece first, then use "Rust reformer" flat black paint on the entire back of the piece and try to get as much of the edges as possible. This will hopefully slow the rust from bleeding on to the front, which I grind after I put down a couple of coats of the rust reformer on the back. The added benefit is that aesthetically, the piece seems to "pop" a little more with the black edges defining the cuts a little better. After the grinding on the front side is done, making sure to tilt the piece in the light to see missed spots, I will quickly wipe the front off with acetone to get any dirt/grime off and then immediately put on color as needed. once dry, I clear coat the entire piece, front and back. I'm still working on getting in to an HVLP setup, so my results are still not where I want them, but most times, they turn out great.

I've used this method now for the last 10 or so pieces I've completed, all of which is hot-rolled 16ga, including the top three on this gallery

[HammerDownJustin]

Did not read everything but I seen after the acid bath you rinsed with water. When I drove a cement mixer years ago we washed our trucks in acid bath. And afterwards we washed them with a heavy soapy water mix. The soap neutralized the acid.Plain water only rinses it off. The soap neutralized it. You could tell if a driver with a newer truck lied because in a week or so his truck would start rusting.

[steelfx]

For those of you who live & work in states with high humidity, you can stage your polished steel pieces & not worry about rust for months by using VCI paper. I have it in 1' squares on my site if you'd like to learn more about it. 1 sq. ft. will protect up to 3 sq. ft. of steel. Just lay it on the steel, with the print side UP, then your next piece of steel, more VCI paper & never worry about rust again! It's been tested out to 4 years by the mfg.

PROTEK-WRAP®-STEELFXPATINAS.COM_-430x430.jpg

Here's a link: http://steelfxpatinas.com/shop/supplies ... top-paper/ 100 sq. ft. for $17.99.

thanks!

Bill

[cosimpson]

Has anyone used a rust neutralizer product?
Loctite Extended Rust Neutralizer spray can.
CRC -CRC - 32 Ounce Bottle, Rust Converter soaking

before clear coating.

I don't know if it cause a problem before staining or Patina.

Just an Idea.

Chris

[steelfx]

Rust Converter Products will Hydrolyze and Convert Oxides to Phosphates, so they will "convert" Iron Oxide (Rust) to Iron Phosphate, which is Black in color.

If the Rust is Heavy, Flaky & Generally "Gnarly", the Converter will turn most of the exposed rust black, then it will readily fall off or peel off & the rusting process (oxidation) will start again.

The "Off-The-Shelf" Converters, like the one you mentioned,are great for tools, tanks, & lots of other things, but
Have NO Place in Rust Prevention or for Use on Iron or Steel That is Going to be Polished, Finished & Top-Coated (Clear-Coated) as Metal Art.

The Best Black Oxide a.k.a (Phosphate Coating), like you see on car parts, tools, etc. is done with high-temp tanks & repeated immersion/rinse/ cycles.

The Cold-Application of Rust Converters is Not Nearly as Durable, nor does it penetrate as deep as the Hot-Application, which would be very difficult to do at home or in a small shop.

Hope that helps!

Bill

[cosimpson]

Bill;

Thank's for your input and makes sense, But if used would it identify the hidden rust with the black spots to clean better?

just playing devils advocate, trying ways to see things we can't see.

Chris

[steelfx]

Bill;

Thank's for your input and makes sense, But if used would it identify the hidden rust with the black spots to clean better?

just playing devils advocate, trying ways to see things we can't see.

Chris

Hi Chris,

Maybe. I haven't found it necessary to do anything like that, but it's worth a try. There would have to be a significant amount of iron oxide present to effect a color change from the converter. Just getting the surface wet with water would darken the rust and make it more visible, but if it's a very small amount of flash-rust, especially if it's hidden in a grinder mark (striation) or edge, it would still be hard to see. Just taking the steel into full sunlight & holding it at different angles is the cheapest & fastest way.

Hope that helps.

thanks!

Bill

[_Ogre]

if your cutting on a water table try using some washing soda in the table water
we have raw steel fixtures sitting on our table for 18 months that have no rust on them
if there is any spot rust it was caused by splashing plain water when filling the table



i use 2/3 of a box each time we change the water

[michmetalman]

We have the same problem, forming under clear coated bare metal and powder coated metal like metallic blue and red. I have come to the same conclusion that it starts on the sides that are tough to sand down. We give ours an acid bath also, so of course the minute you take it out and rinse it off even grinding right away, the sides are gonna start flash rusting. My though is the only way to stop this is to take it out of the acid, rinse it and sand blast it. I'm gonna get me a sandblaster and cabinet to see what happens, but I suspect being able to get the edges of all the metal would pretty much stop the rust.