Sciencemadness Discussion Board - DCM from paint stripper problems

DCM from paint stripper problems

BILLBUILDS - 12-2-2017 at 23:00

Im having problems getting dcm from my paint stripper. its 870g/L DCM 130g/L methanol but its a thick goop which is just impossible to work with. should i add a high boiling compound such as vegetable oil (i didnt check if its miscible, but a use a miscible none the less).

JJay - 12-2-2017 at 23:27

Do you have an MSDS? What method are you using to remove the DCM?

j_sum1 - 12-2-2017 at 23:38

Sounds strange. This shouldn't be hard. The hardest part is getting it into the flask and the residue out. But there are work-arounds for that too. (Including not using a flask.) A simple distillation with mild heat has the DCM/MeOH azeotrope coming over quite nicely.

If you desperately did need to thin it down the best thing to use would be more DCM.

[edit]
One of these is very useful for gel substances.
p.jpg - 4kB

[Edited on 13-2-2017 by j_sum1]

JJay - 12-2-2017 at 23:48

I usually use boiling water to get DCM out of the bottle.

Db33 - 13-2-2017 at 03:04

the method JJay uses is exactly what i used except i actually fixed a 24/40 distilation adapter on top of the stripper can and led to a condenser and used hot water.

dactyl - 13-2-2017 at 18:52

If the above procedures fail, you might condsider adding NaOH and afterward repeat the distillation as described above

JJay - 13-2-2017 at 18:53

Quote: Originally posted by dactyl

If the above procedures fail, you might condsider adding NaOH and afterward repeat the distillation as described above

Oh? Why is that?

Magpie - 14-2-2017 at 12:06

Have you read this?

http://www.sciencemadness.org/talk/viewthread.php?tid=1083&a...

dactyl - 16-2-2017 at 14:33

@JJay
One time I found that when I had little acetone to clean a flask filled of something similar to this described goop after attempting a paint stripper distillation, adding NaOH tends to lossen up the goop a bit.
Since methylene chloride and methanol are unreactive to acetone and the goop would likely not generate anything too volatile adding NaOH and performing the the above again or adding an NaOH solution to the goop and distilling could probably help release more methylene chloride.

dactyl - 16-2-2017 at 14:38

correction: Since methylene chloride and methanol are generally unreactive to NaOH

JJay - 16-2-2017 at 14:41

Quote: Originally posted by dactyl

@JJay
One time I found that when I had little acetone to clean a flask filled of something similar to this described goop after attempting a paint stripper distillation, adding NaOH tends to lossen up the goop a bit.
Since methylene chloride and methanol are unreactive to acetone and the goop would likely not generate anything too volatile adding NaOH and performing the the above again or adding an NaOH solution to the goop and distilling could probably help release more methylene chloride.

The goop in DCM-based paint stripper is some kind of wax. NaOH isn't going to help here.

dactyl - 16-2-2017 at 14:43

Do you know if this kind of wax is the same or mostly so among other brands of paint stripper which have wax and methylene chloride?

JJay - 16-2-2017 at 14:59

Quote: Originally posted by dactyl

Do you know if this kind of wax is the same or mostly so among other brands of paint stripper which have wax and methylene chloride?

According to the reasoning you have proposed for removing DCM from paint stripper, one might as well add soap, sodium hypochlorite, water, or limonene. In the absence of a sound theoretical reason or experimental evidence to the contrary, you're proposing an experiment to add a caustic chemical someplace it doesn't belong for no apparent good reason. Whether I possess omniscience relating to brands of paint stripper or whether you have any expertise on chemistry are irrelevant details; what matters here is whether adding NaOH to paint stripper prior to distillation is a good idea. It's not.

[Edited on 16-2-2017 by JJay]

Boffis - 17-2-2017 at 10:11

The "gloop" you are referring to is usually an aluminium salt such as aluminium naphthenate or aluminium palmatate or a similar salt of a fatty acid. I am not exactly sure what naphthenic acid is but it is widely used to render metals "spirit soluble" for things such as wood preservatives (zinc and copper naphthenates). At higher concentrations these "soaps" are used as thickeners or non-polar liquids such as petroleum spirit in good ol' napalm (as Lieutenant Colonel Kilgore would have it). Calcium and magnesium salts work in some cases and lithium salts are widely used for specialist greases etc.

In summary aluminium salts should be soluble in strong sodium hydroxide but calcium and magnesium salts will not be but its only any good to clean out the flask afterward.

[Edited on 17-2-2017 by Boffis]

highpower48 - 17-2-2017 at 11:07

Quote: Originally posted by dactyl

I believe it was Nile Red or Nurdrage or someone said he used kerosene for clean-up.

highpower48 - 17-2-2017 at 11:11

I believe it was Nile Red or Nurdrage in one of there videos said they used kerosene for clean-up.

macckone - 17-2-2017 at 17:13

Use the can the crap came. Pour out half int a sealable disposable container, i like used spaghetti sauce jars. Then after you get the dcm add the remainder back. Lots of things will thin it out. Aluminum salts can be separated with sodium bisulfate. Which precipitates sodium alum and leaves the fatty acids in solution. Of course thickeners can be a whole host of things. Usually this seperation is not worth it.