Some time ago I distilled some DCM from Klean-Strip KS-3 paint remover (msds: http://www.homedepot.com/catalog/pdfImages/21/21c0034c-c330-...). Whatever polymeric goo they put in the product made an awful mess of my pretty
flask. I tried base washing (NaOH + H2O), scrubbing with soap and water, twisting paper towels, ethyl acetate, acetone, isopropanol, etc. There was
still some junk in there no matter what, so I decided to be a bit more aggressive. I swirled the flask with a small volume of fuming nitric
acid(10-20mL) and let it sit for a week. I've done this with stains especially of coordination compounds and second-hand glass frits, and it has
worked great. Thinking back on it now, this was probably a dumb call...
Not only is the filmy residue still present, I am a bit worried about a nitrated byproduct. There is and was very little of the film present on the
flask, eye-balling it I would say less then a gram.
My plan is to dilute the nitric acid, and throw in some aluminum can pieces or maybe copper scrap (outdoors) to reduce the nitric acid concentration,
then neutralize with base. I'm a bit concerned about there potentially being unstable nitrated organics, I was wondering if anyone had any input on
either: 1) what the polymer is in this product? 2) How to properly deal with/dispose the solution safely. 3) How to actually clean the flask...
Any input would be appreciated.bfesser - 11-12-2013 at 16:31
<a href="viewthread.php?tid=25000#glass"><strong>Topical Compendium</strong> » Other Topics » Glassware
» Cleaning</a>DraconicAcid - 11-12-2013 at 16:53
When I get organic crud in a flask that will not come off, I add nitric acid and boil the bastard. In a fume hood, of course.Sedit - 11-12-2013 at 19:27
I have said it so many times, Put clean sand, water, and a small amount of soap in your flask and swirl/shake the shit out of it. It will clean up the
worst messes you could possibly create and I have yet to see it scratch any glass. bismuthate - 11-12-2013 at 19:46
If you are experienced you could use HF but only as a absolute last resort due to the extreme danger.
I would recomend K or NaOH in denaturated ethanol.
On a side note has anyone cleaned with Cl?Pyro - 12-12-2013 at 00:37
I use a mix of 500ml H2SO4, 25g K2Cr2O7 and 25ml H2O.
Dissolve 25g K2Cr2O7 in 25ml hot water (If it doesn't all dissolve it doesn't matter) then add 500ml conc. H2SO4
then just put some in a dirty flask, swirl put it on all the surfaces and dump the excess back into the bottle. according to Vogel this will even
remove C residue.
bismuthate: HF sounds like a terrible idea! It's extremely toxic, corrosive and worst of all: It will eat or frost your glass.
[Edited on 12-12-2013 by Pyro]bismuthate - 12-12-2013 at 04:18
Dilute Hf is used to etch a miniscule layer of glass of therefor cleaning it.(works like a charm, except with more noxious fumes and corrosivness) http://www.youtube.com/watch?v=9qze4BOsF5k
Although I do say it is not something I would use unless I had no choice.smaerd - 12-12-2013 at 06:23
I appreciate the how to clean the glass answers. The sand trick sounds excellent, I used to use salt to similar effect not sure why I stopped trying
that. Was really hoping for some insight as to what this polymer is, and what kind of waste I have generated and how to properly dispose of that
waste. I'll check around my local disposal centers I guess. It's a super tiny amount but still I would feel like I wasn't doing the hobby with
appropriate intent if I dumped it or put it in the toilet.
Pyro: Mixing oxidizing agents with potentially unstable nitrated/ammonium compounds is something I would like to avoid.
Even if it's a small amount or nothing reacted, I really don't mess around with safety in the home workshop. Especially after reading some of the
horror stories on here.DraconicAcid - 12-12-2013 at 09:22
Dilute Hf is used to etch a miniscule layer of glass of therefor cleaning it.(works like a charm, except with more noxious fumes and corrosivness)
What do you dilute the hafnium with?Pyro - 12-12-2013 at 10:38
I have tried this on caked m-dinitrobenzene (grrr, I hate having stuff in pipettes!) and it takes a long time for it to go away. if it's really hard
to remove it shouldn't be a problem to use chromic acid
try 15% Na3PO4 soln. with a mild abrasive (pumice),
DA: he means HF, not Hf
[Edited on 12-12-2013 by Pyro]blargish - 12-12-2013 at 16:27
I did this same distillation of dichloromethane from a paint stripper called Recochem Heavy Duty Paint and Varnish Remover. The MSDS for it is pretty
much the exact same as yours. I had the same issue with my reaction flask being caked in gooey "petroleum distillates" after the distillation, but I
found that a wash with kerosene was able to effectively remove it from the flask.MrHomeScientist - 13-12-2013 at 07:52
I did the exact same experiment with the exact same paint stripper product as the OP. I also had gunk left over in the flask, and several washes with
kerosene got rid of it nicely for me. A followup rinse with acetone washed away the residual kerosene. I made a video on this experiment as well.
Unfortunately I don't know enough about organic chemistry to comment on what happened to yours. Don't nitrations generally require sulfuric acid to
proceed?
