SoCal Dave Posted January 15, 2014 Share Posted January 15, 2014 I twisted some 3/4" bars, one way and then another direction. I took a wire wheel to it but it still has some deposits that a tough to remove. I tried a 120 grt flap disk but it's impossible to get deep into the twisted area. Is there a chemical or solution, say vinegar, that would remove this scale. I either have to press to hard with the wire wheel and it is to slow and I don't want to grind it off to a new shinny surface. post edited to replace the word slag with scale, the product he is trying to remove. Quote Link to comment Share on other sites More sharing options...
Glenn Posted January 15, 2014 Share Posted January 15, 2014 You can clean some scale off (careful about tempering the piece) by dipping in water. A wire wheel or flap disk will get some. Vinegar soak will remove some. Electrolysis will get some of the rust. Tumbling will get some. Sandblasting will get the most if the piece can be blasted with sand, or other media. Usually a combination will do the most good. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 15, 2014 Share Posted January 15, 2014 Scale not slag; slag is quite different. (and you can run into it if working lower grades of real wrought iron) Quote Link to comment Share on other sites More sharing options...
jmccustomknives Posted January 15, 2014 Share Posted January 15, 2014 quite often you can use your torch and make the scale just pop off by running the flame down the piece. Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted January 15, 2014 Author Share Posted January 15, 2014 Sorry guys, it's scale. At my age, if a word is close, and I give my brain a few seconds to compute, and nothing else comes up, I'll stick with it. Quote Link to comment Share on other sites More sharing options...
Metalsmith21 Posted January 16, 2014 Share Posted January 16, 2014 Wire brush the piece while its hot Quote Link to comment Share on other sites More sharing options...
petere76 Posted January 16, 2014 Share Posted January 16, 2014 SoCal, Acid wash in vinegar (food service) overnight, soft brush off the scale, and wash in soapy water. It helps if you aggressively get rid of the scale you can with a wire brush before the acid bath. Good luck. Peter Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted January 16, 2014 Author Share Posted January 16, 2014 Proportions of vinegar and water or is it straight vinegar? Quote Link to comment Share on other sites More sharing options...
781 Posted January 16, 2014 Share Posted January 16, 2014 Oh minus or ph down and warm water is faster than vinegar. Have to do whole piece or will look strange. Quote Link to comment Share on other sites More sharing options...
Jerry W. Posted January 16, 2014 Share Posted January 16, 2014 I use 20% vinegar purchased at the garden center. I will let my piece soak overnight. A quick dry and dust off with the wire brush on the grinder and it looks great. It will rust after this process amazingly fast. I have been very pleased with the results. Quote Link to comment Share on other sites More sharing options...
jeremy k Posted January 16, 2014 Share Posted January 16, 2014 Wire brush the piece while its hotI agree - vigorously wire brush while at a dull red heat with a block brush. Quote Link to comment Share on other sites More sharing options...
petere76 Posted January 16, 2014 Share Posted January 16, 2014 Socal, I use straight kitchen grade (cheap) white vinegar. It works great. After an overnight soak most of the scale has already fallen off and a light brushing with a soft bristle brush removes the rest. Outside pieces I usually paint. I have heated and hot oiled some flat plates for inside pieces like candle stands and table coasters. They came out looking real good with a tempered color scheme. Once you get all the scale off a piece the finish looks much better. Peter Quote Link to comment Share on other sites More sharing options...
lupiphile Posted January 17, 2014 Share Posted January 17, 2014 i use phosphoric acid. it doesn't require neutralizing, it won't etch the metal. works about ten times faster than vinegar and it's realitively safe. zep prep and etch is a commonly available solution. dilute it 1:3 with water. Take care, Matt Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted January 17, 2014 Author Share Posted January 17, 2014 I tested the vinegar solution on two of my twisted legs. I soaked them for 24 hours and then wire brushed them. They came out great. The scale came off when brushing and left a shinny metal finish. I rubbed them with a layer of Johnson's wax to reduce the rust factor until I'm done assembling the table. I ran another test with the two remaining legs, but this time, I added some baking soda to the solution. Lots of people suggested this, so I'll give it a try and report on it's effects later. Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 17, 2014 Share Posted January 17, 2014 I vote for phosphoric acid, it doesn't "remove" oxidization it removes the oxygen, returning the rust to steel/iron. Read a bottle of Naval Jelly. I use lab grade 99.97% phosphoric acid diluted in varying degrees depending on how scaled or how fast I need it to work. Naval Jelly works very well but it's intended to be painted on so it has a jelling agent and surfacants. It works in a bath if you dilute it so it can flow into small spaces. A few words of warning about phosphoric acid above about 20%. It's a powerful acid all safety precautions are in order, PPE includes neoprene gloves, apron, face shield and eye protection underneath, boots, rubber is best. Phosphates work because it's a very reactive element, it bonds far more easily with oxy than most other things like iron or carbon hence it deoxidizes rusty steel. It also bonds very easily with calcium like in your BONES, do NOT get it on you and heavens forbid not IN you! At low concentrations phosphoric acid is used as concrete wash, it'll clean and whiten your floor like magic. If you were to spill phosphoric acid from the bottle on the floor it will react EXPLOSIVELY! As I recall Naval Jelly is 30% phosphoric acid and probably only foams on concrete but I haven't tested it. It REALLY works but it can be DANGEROUS be careful. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Glenn Posted January 17, 2014 Share Posted January 17, 2014 When using ANY ACID or CHEMICALS, be sure and protect yourself and others from danger and harm. Personal protective clothing is a must. Proper clean up and neutralization is a MUST. Safety first - always. Quote Link to comment Share on other sites More sharing options...
ptree Posted January 18, 2014 Share Posted January 18, 2014 Anybody wonder how the vinegar works to remove the scale? It is a process called pickeling. When the mild acid in the vinegar reacts with the steel under the scale it disolves the steel a little, and in the reaction hydrogen gas is evolved. The gas bubbles "Pop off" the loosened scale. Pickeling from the use of vinegar just as in using vinegar to pickel veggies:) By the way warm work faster then cold and boiling works really fast. Strong phosphoric at say 185F will pickel scaled forging really quick, but you better have a really good ventalation system. We used boiling caustic soda solution to clean the shop oils off and then 185F strong phosphoric at the valve plant to pickel, followed by a 145F amended phosphoric to convert the surface to a micro iron phosphate surface, followed by a warm soft water rinse, and then into the air dry oil. Made the valves a nice mat black that would not rust in storage. We ran millions of tons of steel forgings thru that line. Quote Link to comment Share on other sites More sharing options...
Chinobi Posted January 18, 2014 Share Posted January 18, 2014 can anyone elaborate on adding baking soda to the vinegar to aid scale removal? that strikes me as counterproductive. vinegar alone works, I have a huge jug in my garage from Costco for just such purpose. baking soda alone is reported to work "when in a concentrated alkaline solution" (courtesy of wiki:baking soda). and baking soda is amphoteric, reacting to neutralize both acids and bases. this leaves you with sodium acetate, water, and CO2. sodium acetate doesn't seem to be particularly useful for anything in this context. This is the engine that drives the old 'volcano' science fair project, all that foaming you see is the acid and base reacting to eliminate each other. found a couple of other old threads that discuss neutralizing shop acids (muriatic, sulphuric, and vinegar etc) by [carefully!!!] mixing in baking soda '?do=embed' frameborder='0' data-embedContent>> '?do=embed' frameborder='0' data-embedContent>> ptree, is that similar to the 'black phosphate' finish that you can find on some harbor freight hardware? Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted January 19, 2014 Author Share Posted January 19, 2014 After soaking two bars in a solution of vinegar with Baking Soda for 24 hours, I discovered a few differences. The solution was foaming a little around the bars. The bars came out with a very flat black coating. I can't tell if the scale came off any easier. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted January 19, 2014 Share Posted January 19, 2014 Vineger is an acid...baking soda is alkaline..adding alkaline to acid neutralizes the acid.....of coiurse depending on the proportions added. Quote Link to comment Share on other sites More sharing options...
swedefiddle Posted January 19, 2014 Share Posted January 19, 2014 Phosphoric Acid is in Coca-Cola. I use Phosphoric Acid to stop/neutralize rust on car/truck bodies. Phosphoric Acid turns the rust Black. Quote Link to comment Share on other sites More sharing options...
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