HF paint stripper on data sheets lists Methylene chloride 70>85% Methanol 10>25% Hydrofluric acid. 5%
Previously I have found the chemical splits. Is there a particular method to properly blend all 3 parts?
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6$\begingroup$ Offhand, I can't think of a more dangerous DIY activity than what you're proposing, if in fact this is headed that way. If you're just curious, disregard my comment. $\endgroup$– Todd MinehardtCommented May 20, 2021 at 22:07
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1$\begingroup$ Sorry I’m fully aware of the dangers. I forgot to mention I work with this everyday in well extracted rooms. We use this for the paint removal of alloy/steel wheels which require a acid based stripper to remove the epoxy primers applied from factory. We currently use around 2000litres every 4-6 weeks. $\endgroup$– Will RandleCommented May 20, 2021 at 22:16
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3$\begingroup$ We do have all the PPE and anti HF gels inc shower room. Getting back to the point and the reason for my question is costs across transportation of this blended stripper have increased massively. However we are able to order the raw materials in for half the cost and mix on site if the process was straight forward or is there a particular method? $\endgroup$– Will RandleCommented May 20, 2021 at 22:21
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$\begingroup$ Why do want to blend all "3 parts"? $\endgroup$– Nilay GhoshCommented May 21, 2021 at 2:26
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$\begingroup$ The mix is available to purchase but costs have doubled for various reasons. The reason for mixing is the raw materials are half the cost. Paint strippers without the hf, in particular for alloy wheels do not remove the primer and with the hf we are able to strip wheels in less than 30mins. Our process requires 300plus wheels per week to be stripped and approximately 2000litres of chemical per month. $\endgroup$– Will RandleCommented May 23, 2021 at 14:36
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It is not clear how reliable the concentrations given in the SDS are. It is not uncommon to give a range, but actually manufacture product at one end of the range.
I would take 25 parts of methanol and 70 parts of dichloromethane and add hydrofluoric acid till it becomes cloudy - then back off (add some more CH$_3$OH + CH$_2$Cl$_2$). You may be able to add 4.6 parts of hydrofluoric acid (round up to 5 for the SDS).
The solubility of dichloromethane in water is 1.60% at 20$^o$C and the solubility of water in dichloromethane is 0.24% at 20$^o$C. Ref 1 The solubility of dichloromethane in water increases as the temperature decreases. Ref 2
One unknown is the concentration of hydrofluoric acid and whether higher concentrations of HF are more easily dissolved in this mixture than lower concentrations. The SDS may not give you useful information, but I suggest trying to use the most concentrated HF available - you can always dilute it, and H$_2$O is no friend of this combination.
Methanol and water (and thus, probably also hydrofluoric acid) are miscible and so are methanol and dichloromethane. A recent question on StackExchange (Ref 3) gave a ternary diagram of water-methanol-dichloromethane:
The line separating the one-phase (M) from the two-phase regions (I) does not go all the way to the top, but you can see that there are homogeneous mixtures with a lot of water, methanol and dichloromethane.
The Safety Data Sheet is required to list hazardous ingredients, but not non-hazardous materials. Some stabilizer might be added, hidden in the 15% range of dichloromethane and 10% range of methanol, that could keep the mixture homogeneous. One compound that comes to mind is propylene glycol. If the commercial product is cloudy, it might be stabilized with a thickener like guar or xanthan gum. Wax has been used as an evaporation inhibitor in paint removers containing dichloromethane; it might also act as a thickener and stabilizer.
Ref 1. https://macro.lsu.edu/HowTo/solvents/Dichloromethane.htm
answered May 21, 2021 at 3:54