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So what options do I have??? Dross removal & clean up.....

Posted: Wed Jun 07, 2017 6:47 pm
by Steambike
I am wondering how you guys clean & prep your pieces for paint / powder / whatever you finish with.......
So far I have been using a "flap" disc on my grinder which works ok but doesn't leave a nice finish, i tried wire wheels and the finish is better and it's quicker but the resultant "porcupine" look doesn't suit me :)
I have a ton of reasons for avoiding the Muriatic acid, kids pets -30c winters to name a few......
I figured a drum sander would be the way to go, but that seems like it may not work as well as I had hoped for..based on other posts... sand blasting is I guess a possibility, i have a small cabinet, but not big enough or powerful enough (compressor wise) so I am considering flap disc followed by drum sander.......or possibly building a "wire wheel machine"
So please, aside from the acid, what do you guys do???
I also have to get my cuts better so there is less dross!

Re: So what options do I have??? Dross removal & clean up.....

Posted: Mon Jun 12, 2017 3:33 pm
by larrycameron44
Hi, I don't use muriatic acid but do use a 150 litre container of water mixed with some sodium bilsulphate. It use probably 4 cups in that and add another 2 cups maybe once a month. Soak 24 hours and the dross just wipes off. How safe is it? It's a granular white powder that swimming pool companies use to adjust water acidity.
You can dip your hand in it, if you have a cut, it will slightly sting so it is very diluted.
I know you said an alternative to acid but just another thought.
You mention that you have a lot of dross. Let us know what thickness you are cutting and what plasma source, amps, ipm, volts etc and we can help more. But generally speaking dross is caused by to much height and too slow.

Another method I saw recently to remove dross was a needle scaler pneumatic. A video was posted showing use. It worked well.


Re: So what options do I have??? Dross removal & clean up.....

Posted: Tue Jun 13, 2017 12:18 am
by Gamelord
MSDS info:

Sodium bisulfate is a diluted crystalized version of Sulfuric Acid which is very irritating to the skin and can cause severe eye damage if contact occurs. Also, swallowing the chemical can cause symptoms, such as diarrhea, vomiting, and low blood pressure. In addition, it is considered acutely toxic according to the U.S. Environmental Protection Agency as noted in the Pesticide Action Network of North America database.

First-aid measures include seeking immediate medical attention and not inducing vomiting if the chemical is swallowed. Also, MedLine Plus notes to immediately drink water or milk unless otherwise instructed by medical personnel or if the person is unable to swallow due to convulsions or vomiting, for example. If the chemical gets on the skin, wash with water for at least 15 minutes. If the chemical is inhaled, move to an area with fresh air.

Re: So what options do I have??? Dross removal & clean up.....

Posted: Wed Jun 14, 2017 4:51 am
by larrycameron44
Interesting as it is for sale at all our swimming pool supplies shops and hardware stores. It is also commonly called "ph Decrease" as it is used for lowering the ph if your swimming pool :)

I guess if you put the crystals on your skin or in your eyes, these things as Gamelord points out would happen. But 2-4 cups in 150 litres of water, it is very diluted.

Larry Cameron

Re: So what options do I have??? Dross removal & clean up.....

Posted: Wed Jun 14, 2017 1:35 pm
by Steambike
That would be an interesting alternate to muriatic, so thanks for that, but I think i'll stick with mechanical methods for now......i'm going to try the needle scaler for some bits too!
I will post some pics of my cuts, it dawns on me that I don't know how much dross is too much....maybe it's acceptable????
I will also post up my settings and see what you guys are the settings I can remember off hand (basically book settings)
I'm running a Hypertherm powermax 45xp on 45A at 250ipm with finecut consumables and currently cutting some 16 gauge cold rolled sheet......

Re: So what options do I have??? Dross removal & clean up.....

Posted: Sat Jul 01, 2017 1:38 am
by steelfx
@ Steambike: Check out this post for an alternative to flap-discs on an Angle-Grinder. I use mine all the time & it's well worth the investment. viewtopic.php?f=81&t=12130&p=66267&hilit=flex+burnisher#p66267
Media Blasting will lead you to the poor-house. It takes too long (waaaaay too long) and it leaves a matte finish, which then has to be brightened up, so you've gained nothing. Disclaimer: The FLEX® Burnisher is not a good option for removing mill-scale. It's better than a flap-disc or an AVOS® Disc, but the abrasive will "load-up" with the mill-scale, which is just a bunch of oxides & scale that's actually harder than the carbon steel beneath it.

Have you ever puked? You know that burning sensation in your throat, mouth & nasal passages? It's muriatic acid. Technically, it's hydrochloric acid, which is the same thing as muriatic acid. Hydrochloric Acid is the main component of a human's stomach. It's not that dangerous if handled respectfully. There's a LOT Worse Acids out there, and muriatic acid is a necessary evil when dealing with heavy rust on older steel or Mill-Scale on new HR Steel. Once you've mixed it 1:1 with water, there is no appreciable odor, (I can't smell it at all at that ratio).

The main thing to remember is this: Keep Your Tank Covered!! The off-gassing of the hydrochloric acid will lay down a rust film on any ferrous metal within 50 feet! If you don't have a cover or don't want to make one, buy a few hundred ping-pong balls and cover the entire surface of liquid, one-layer thick. You can find 'em online really cheap. That will prevent >90% Off-Gassing. They make special HDPE Plating Tank Balls, but they're really expensive. Any hollow ball (with the exception of wiffle balls), that's made of any plastic will work. Styrofoam balls won't work...too porous. The smaller the balls (spheres) that you use, the better, as the smaller balls minimize negative space. Bubble wrap would work, but may tend to bunch up and shift in a breeze. You could thread some tie-wire through the edge to make the bubble-wrap sheet more rigid.
At some point, maybe're realizing that the old saying, "Time is Money" is really true, and you will try muriatic acid and wonder why you waited so long. Don't buy the unscented variety of muriatic acid. Too expensive & too weak. tank is a Rubbermaid® HDPE, heavy-wall, 250 Gallon Water Trough, Oval in shape. I only have about 4"-8" of liquid in it, I don't fill it to capacity. I started using that because I could fit my larger pieces in it. You could make a nice tank from 4"X4" lumber & a shower liner or 'in-ground' water-feature liner. Those liners are not too expensive & are totally impervious to the acid. Pond Liners are so heavy that you could actually cut a piece for the top/cover, too. When your acid bath gets crusty and gross (and it will), add some water & tip it over in the dirt. It won't harm groundwater, as hydrochloric is actually a gas, suspended in water. It will "disappear" in a few minutes. Don't empty your tank on concrete, though...unless you want the 'rusted concrete look'. (Some folks pay a LOT to get their concrete stained)!! And, no need to neutralize with CaCO3 (Calcium Carbonate), a.k.a Lime or NaHCO3 (Sodium Bicarbonate a.k.a Baking Soda.

You may see a few posts where guys are dipping their steel pieces in a baking soda/water bath after removing from the acid bath. Totally unnecessary. Absolute Waste of Time. ZERO (0%) Acid will remain on your steel after rinsing with water. Zero! Just remove your steel pieces one at a time, rinse both sides w/ plain water & immediately force-dry with clean, dry, oil-free compressed air & set aside, ready to be shined up. If you're using a rusting patina, there's no need to shine the steel, just as long as it's good & clean, you're 'good to go'.. Thanks! Hope this info helps a little.

Re: So what options do I have??? Dross removal & clean up.....

Posted: Sat Jul 01, 2017 1:59 am
by steelfx
p.s. I can tell you from firsthand, everyday personal experience, using a multitude of Dry Acids, and 7-8 Different Liquid Acids at 99% Purity/Strength, I'd rather work with the Liquid Acids ANY DAY over the Dry Acids. Dry Acids and Dry Oxidizers are dusty. When you inhale or inadvertently get any of that dust on your lips, tongue or eyeballs, it is F-ing Miserable! With a Capital "F"! And the 'wash-up' & recovery time is considerably longer than what it would be if you were subjected to a little splash of a liquid acid.

Note: My patina's acid content, in almost all cases, is less than 1/10th of 1%. A few are measured in PPM, and a few others, including my Dyes & Stains Have Absolutely No Acid At All. I don't make or sell a single patina, in either liquid or gel form that will burn your skin.

Liquid Chemicals (Acids in Particular), in a Lab or Production Setting are much, much safer to handle & be in the proximity of, than dry acids. And, when you consider that you can remove ALL Mill-Scale from Both Sides of a piece of HR steel in as little as 30 Minutes, there's no reason to use dry acids, even if they work faster. I have not ever used Sodium Bisulfate for any of my products or for mill-scale removal, but if it's faster than 30 mins., I may be tempted to try it. Nah...I'll stick with what I know works. GRIME GIT'R™ is a Great De-greaser & will also remove mill-scale. It is just the right amount of Concentrated Phosphoric Acid & Distilled Water, with a Surfactant & Preservative. I sell it at my cost to make +10%. And, how's this for high-pressure sales?....I prefer Muriatic Acid for mill-scale removal. One Reason Only: It Works Faster. Thanks again...Bill

Re: So what options do I have??? Dross removal & clean up.....

Posted: Sat Jul 01, 2017 9:58 am
by little blue choo
Great information Bill. Thanks for your expertise. By the way I love my muriatic acid.


Re: So what options do I have??? Dross removal & clean up.....

Posted: Sun Jul 02, 2017 3:56 am
by steelfx
You're very welcome...Hope I wasn't too long-winded! :lol:

Re: So what options do I have??? Dross removal & clean up.....

Posted: Fri Aug 11, 2017 7:22 pm
by plasmartist
I second the the acid for removal. Its dirt cheap for anyone to buy from a home improvement store. And I have noticed leaving parts over night in a diluted solution softens slag to the point I can remove it with my finger nail. For larger plate like 3/8 and half, I found a neat trick- I hit it smack in the center with a sledge hammer and all the dross flies off it; (keep in mind this is AR500 plate so that may have something to do with it, also I cut with the water touching the surface). When I cut with finecut consumables I have find that a quick hit with a 6" wire wheel throws the dross quickly then I follow up with a grinder affixed with an arbor extension and flap disc (the extension allows me to position the flap disc flat on the work piece to give an even finish). BTW american made wire wheels aren't as bad at throwing the wires as the harbor freight or other chinese ones. I'll never forget the day I walked in from the shop and my wife asked why I was bleeding from my neck.