Author Topic: cleaning glass  (Read 1610 times)

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  • Guest
cleaning glass
« on: November 03, 2003, 01:03:00 PM »
i was in this lovely 2nd hand store in melbourne the other day purchasing a few glass items (i got a 30cm coil condenser for 35 bux!!!) and the old fellow in there said someone once told him to use a mixture of hydrochloric, sulphuric and nitric acid to clean dirty old glass lab gear...can anyone think of a good reason not to do this as in it being lethal or whatever...(yes, i know to rinse well with water afterwards...and not to drink it etc.)


  • Guest
I can't give you a reason not too, but hose...
« Reply #1 on: November 03, 2003, 01:22:00 PM »
I can't give you a reason not too, but hose things don't work as well as solvent, like acetone or something like that, salt and water also works well, the only reason I would use these over your Acid Cocktail is that it's alot easier, and using tons of acid like that is bad for your respitory system, I wouldn't use Hydrochloric acid to clean any thing personally, and sulfuric acid is really syrup like cosistency and it will take alot of water to get it all out.


  • Guest
Cleaning Glass
« Reply #2 on: November 03, 2003, 02:58:00 PM »
Ok  the best way to clean glass ist to put it 2 week into a IPA bath followed by 3 week in HCl bath.

But if u want it clean and fast use this one.

Give konz. HCl into your glassware , not much , just enough to shake it that every dirty place can reached. Now add the same volume 30%H2O2 but be careful, very exothermic reaktion after a few minutes. After reaktion is done your glass is clean like new. A good recovery cure is a 2 week bath in 1/3 konz. HCl .
Thats the way we work.

If it is only Ca dirt  a HCl bath is enough .....


  • Guest
Well I think what the guy in the store meant...
« Reply #3 on: November 03, 2003, 03:07:00 PM »
Well I think what the guy in the store meant is Aqua Regia, a combination of 3 parts concentrated HCL and 1 part concentrated HNO3(Nitric Acid).  It is a very powerful cleaner for extremely stubborn stains.  But most stains can be cleaned by much less powerful and dangerous cleaner then Aqua Regia, such as just HN03.  For general cleaning Alconox works well.  Now once you feel you have throughly cleaned the glassware and rinsed it with DH20...wet it once again and if the water coats the surface of the glassware evenly as opposed to beading up or forming droplets on it you have sucessfully cleaned off any contaminents that you would need to be concerned.  For quick drying of wet glassware and therefore preventing water spots from forming a quick rinse with acetone works well.  Remember to clean glassware immediately after use and it should stay in like new condition.  Good Luck.  Pyrex out cleaning his glassware ;-)


  • Guest
Aqua Regia IS the big daddy
« Reply #4 on: November 03, 2003, 03:30:00 PM »
If you require EXTREME clean..the aqua-regia is the way is the cleaning agent of choice in analytical labs, especially where ng amounts of trace metals are being analysed.

I would suggest aqua-regia, followed by an IPA bath.



  • Guest
Additional Cleaning Methods
« Reply #5 on: November 03, 2003, 04:55:00 PM »
As threads asking this question occur on approximately a monthly basis, there are numerous threads to bee found using the search engine which will answer your question  :(  Some previously unposted information about cleaning glassware from the Chemical Formulary  ;)

Cleaning Laboratory Glassware
Formula No. 1
For bottles, use a test bottle washer or place the bottles in a suitable rack with perforated or slotted cover and immerse. A cleaning solution made of 1 oz. of a good grade of washing powder to a gallon of water and heated to 130°-150° F. will be found satisfactory. Scrub the inside only with a brush having soft bristles. Rinse in hot water to remove all traces of the cleanser and invert the bottles to drain. Do not soak the bottles too long.
When very dirty, greasy bottles must be cleaned, a very good cleaning solution can be made by dissolving 31/3 oz. of potassium dichromatic in 1 qt. of water, and slowly adding to this 1 qt. of sulphuric acid. This solution will remove all traces of grease after sufficient soaking, but care must be taken to keep it from prolonged con­tact with the outside of the necks, be­cause of its effect on the enamel in the lines and numbers.
No. 2
Take a 10 oz. cake of a good grade of cleaning and polishing grit cake soap, such as "Bon Ami" and pul­verize it to a powder with a mortar and pestle. Cut a 12 oz. cake of a good grade of rosin laundry soap, such as "Octagon," into thin slices and add just enough water to cover the mass. Slowly heat on a hot plate until the soap has dissolved in the water and a clear solution results. Add this liquid soap mixture to the powdered grit cake in a beaker or earthen jar, stirring the mixture well. Allow to stand overnight or until the resulting mixture has solidified into a soft mass. The mixture can then be easily applied to the wet glassware in the usual manner with a brush or the hands, scrubbed thoroughly and finally rinsed in running water. It is only necessary from time to time to add small quantities of water to keep the mixture at the proper consistency. To make a larger supply increase the quantities accordingly.

Removal of Tars and Carbon Residues from Glass Equipment
Distillation flasks and other equip­ment which have contained tars, or flasks which have been used for dis­tillations in which tars and carbon residues are formed, can usually be cleaned when all other methods fail by treatment with a hot concentrated solution of sodium hydroxide to which small amounts of potassium per­manganate have been added. The strong oxidizing powers of perman­ganate solutions are especially effec­tive on tarry materials. At times it may be necessary to repeat the treat­ment, and to boil the solutions for a time. This method has been found to be much superior to those using boil­ing acids and solvents, and much better than alkaline solutions by themselves. The economy of materials employed makes it available to all.
Cleaning Organic Smears-Tars, Etc.-from Apparatus
Put the dirty beakers, test tubes, distilling flasks, etc., into a large evaporating dish containing concen­trated commercial sulphuric acid heated to 200-225° C. (400-435° F.). Small quantities of nitric acid should be added whenever the heated acid becomes black in color. Large beakers can be turned around sufficiently to bring all parts into the hot acid. When the apparatus is clean, remove (use a glass rod) and allow the articles to cool before rinsing in water. This cleaning solu­tion is not satisfactory for petro­leum products. This solution is much more economical than chromic acid solutions-the same acid can be used many times.
Caution: Have beakers, flasks, tubes, etc., pointed away from the operator while they are being put into, the acid. Sometimes the reac­tion with wet, very dirty apparatus causes a spattering of acid from the open end of the vessel. The acid should be kept in a glass-stoppered bottle when stored.
Cleaning Flasks or Other Apparatus from Baked-In Carbon Deposits
Put a small quantity of potassium chlorate in the dry flask; heat the flask gently in a Bunsen burner flame until the chlorate is barely melted; rotate the flask so that the molten chlorate comes in contact with the carbon. The quantity of chlorate to contact the carbon resi­due is surprisingly small. After cool­ing. dissolve the remaining mixture in water. Caution: Use this only on the solid carbon stain that will not wash out or that cannot be removed by ordinary mechanical means.
Chromic Acid Cleaning Mixture
This is needed for apparatus such as burettes, etc., which cannot be immersed conveniently in a vessel of hot sulphuric acid.
Add 1 1. of cone. commercial sul­phuric acid to 50 g. chromic acid dissolved in 25 cc. of warm water. There will be no trouble from crys­tallization of salts from this mix­ture. This mixture, without heating, removes organic material after a few hours of contact. More chromic acid can be added whenever the so­lution loses its red color. Caution: Keep in a glass-stop­pered bottle. The reason: absorp­tion of water from the air reduces the activities.
Cleaning Laboratory Glassware
lodoform stains and odor may be removed by washing glassware with a solution of potassium or sodium hydroxide and rinsing it with a small amount of alcohol. Of course, the final step in this cleaning opera­tion. as well as in all others to be described, is thorough washing with soap and water. Ferrocvanide or iron stains are easily and rapidly removed with a solution of potassium hydroxide. Lime deposited by lime water or similar preparations can be removed from glassware with diluted solutions of acetic acid or nitric acid. Deposits from lead subacetate solution can also be removed with these cleansing agents.
Deposits of soluble metallic salts are usually readily removed by thorough rinsing with water; how­ever, in some cases, a small amount of hydrochloric acid may facilitate the cleansing. Insoluble or practi­cally insoluble salts may be re­moved from glassware by dissolving them with the appropriate solvent which differs for each salt. Metallic soaps, such as oleates and lead plaster, may be removed by oil of turpentine.Oils, resins, balsams, and similar resinous bodies can usually be re­moved with soap, but in some cases a solution of potassium hydroxide may be required.
Collodion may be removed by peeling it off the glassware. If, how­ever, the film adheres firmly, a mix­ture of ether and alcohol will remove it. In the case of adherent gutta­percha film, chloroform should be used as the solvent.
Sawdust is one of the best mate­rials for removing petrolatum, lard, or other greasy substances from mortars and ointment tiles. Paper cleansing tissues are also excellent for this purpose. After the greater part of the grease has been removed with the sawdust or paper, the glass­ware should be washed with soap and water.

:)  ;)  ;D


  • Guest
« Reply #6 on: November 05, 2003, 09:53:00 PM »
Household bleach works really well at cleaning thin layers of baked on organic crap. I was surprised to find this one out, just let it sit for a few hours.

Acids work great at removing manganese stains and lots of other inorganics. Sulfuric acid with a bit of water can work well as a hot oxidizer as well.. care must be used. Lots of other ideas here work well too. Take great care using cleaning solutions with hydrogen peroxide... violent rapid decay of conc H2O2 is really nasty!!!


  • Guest
« Reply #7 on: November 06, 2003, 07:29:00 PM »
Bleach isnt necessarily such a good idea, as it can scar the inside if your glass because of its abbrasiveness. It doesn't seem bad, but after a while your glass gets weakened...especially when under pressure or immense heat like swim uses(had a VERY expensive 4 neck 12 liter flask shatter because of this) >:(  :(


  • Guest
« Reply #8 on: November 07, 2003, 01:51:00 AM »
Can someone verify AngelX's comment? I've never heard of NaOCl being abrassive or damagaging glass. I also use my glass under such immense heating/thermal difference loans but have never had any glass shatter as a result...


  • Guest
I'm with chromic
« Reply #9 on: November 07, 2003, 04:31:00 AM »
The only thing I have experienced as being bad for glass is to repeatedly reflux strong NaOH solutions in it, after 50-100 hours of such usage you can see the glass being thinner and somewhat hazy below the surface level.


  • Guest
NaCl as an abrasive
« Reply #10 on: December 01, 2003, 03:12:00 AM »
A quick search didn't reveal this, so I thought I'd pass it on.

If you've got some really tough stains / burned-on crud that you seemingly just can't shift, try this:

To a reasonably dry (and presumably dirty) flask, pour in a small handful of table salt (ordinary NaCl), along with a solvent like acetone or toluene (whatever you think the crud is most soluble in).  Swirl swirl swirl.  The salt acts as a gentle abrasive removing the crud, the solvent helps the process.  This is my trump card if nothing else works, it has worked every time (sometimes requires more effort than other times).

At least, I *think* the salt is a gentle abrasive, I haven't had any flasks cleaned this way implode under vacuum *yet*.


  • Guest
« Reply #11 on: December 01, 2003, 02:13:00 PM »
Ingenius spectral, thats exactly how I clean my bong...

NaCl and Acetone


  • Guest
don't try that on a plastic
« Reply #12 on: December 02, 2003, 03:39:00 AM »
dont try that on a plastic bong anyone, it may dissolve the plastic! (may not too depending on the plastic, but plastics can be pretty sensitive to ketones/acetone).

At least if you are going to do it, then try a drop of acetone on an out-of sight bit to test if it dissolves it.


  • Guest
« Reply #13 on: December 02, 2003, 08:46:00 AM »
What kind of lame-ass bee uses a plastic bong?  ;)

Anyway, I just remembered back in quantitative analysis we used this stuff called Chromix, however, I have since forgotten what the consistency was.

That was some very not-fun nasty shit!


  • Guest
bee careful!
« Reply #14 on: December 02, 2003, 02:20:00 PM »
uh, the solution auntyjack mentioned in the original post is the "notorious" pirhana solution, isn't it? there's a terrifying story about use of such a cleaning solution in

Post 434577

(jimwig: "that's what my glass man here said.", Chemicals & Equipment)

this scared the shit out of me when i saw it. no pirhana solution for me!


  • Guest
tetra maybe?
« Reply #15 on: December 10, 2003, 08:06:00 AM »
all this talk of bhongs reminds me...the other day swiaj decided to see what would happen if he sprayed his disgusting, black bhong stem with some, this may not mean much to some people but swiaj's jaw hit the floor as with one spray, all the black shit fell off...i mean just fell straight soaking, no scrubbing...spray,plop...that's it!!  anyway, since tetra leaves no residue it seems like a good candidate for glass cleaning...couldn't find the horror story about the pirana solution but will try again...hope it's horrible...have fun, bye for now,
                                      aunty jack


  • Guest
sodium hydroxide
« Reply #16 on: December 19, 2003, 09:14:00 PM »
Usually SWIM uses sodium hydroxide to clean his glass, its usually cheaper than wasting solvent. After the wash with NaOH then use water and distilled water, it burns grease like magic. No wonder NaOH is used as drain unclogers.


  • Guest
« Reply #17 on: December 20, 2003, 02:08:00 AM »
I use CrO3, H2SO4, heated in an ultrasonicator it gets the shit clean!!! Takes bout ten sseconds.

Marleybob-- I thingk you are thinking of the shit I use!!!
 Chromium trioxide in concentrated sulphuric acid!! Yes definately some nasty fucking shit alright! But it works
like nothing else!!

Ahh hell Lugh beat me to the punch! Actually I think lugh has an error there.. It was posted here before I know I posted htis cocktail once beofe after finding it in a belart catalog.

Edit: Ok, Ok I'm sorry I did post this back in 02 but failed to specify that the packet from belart then was a vial of chromic acid.