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Recently I started renovating a bicycle. The frame has been painted probably over 30 years ago, and despite holding well, big patches of rust are showing. So it's time to give the bike a new paint job. And before that, I need to sand the frame and remove the current paint.

Sadly it came to my attention that some bikes around that age have lead paint. Toxic, obviously.

I'm by no means a pro chemist. Far from that actually: if you show me a bunch of formulas, I might understand it, but I'm not skilled for manipulations neither properly equipped.

Provided that I can scratch a bit of that paint with sandpaper, what's the easiest way to test it for presence of lead? Apparently some lead test kits exist, but they're incredibly hard to find here.

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  • $\begingroup$ Nice question! But don't you think it's a little late to worry? Unfortunately, if it is lead paint, then you've been exposed to it for 30 years. $\endgroup$ – M.A.R. Jun 13 '15 at 8:36
  • $\begingroup$ Good point! I've owned that bike since last year only, so I really know nothing of its history. Hopefully its previous owners were not intoxicated, but as I'm about to sand it, I want to make sure I'm not inhaling lead dust. And also that I'm not releasing that into the environment. On top of all that, I'm curious :) $\endgroup$ – aspyct Jun 13 '15 at 8:46
  • $\begingroup$ technically you can, but it requires special equipment. $\endgroup$ – permeakra Jun 13 '15 at 10:56
  • $\begingroup$ Anyway, you can safely use abrasive blasting as long as you use proper protection (a well fitted respirator and protective goggles.) $\endgroup$ – permeakra Jun 13 '15 at 10:57
  • $\begingroup$ @permeakra Any guidance as to what respirator I should use? I have FFP2 NR D here, would that be sufficient? $\endgroup$ – aspyct Jun 13 '15 at 12:51
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Two chemicals are used in lead test kits: sodium sulfide or a rhodizonate salt. Sodium sulfide should be easy to obtain (or synthesize), and is useful for light-colored paint, as it produces a gray or black color change. Potassium rhodizonate can be synthesized from inositol, but you might be better off getting sodium rhodizonate, e.g. from Sigma-Aldrich for ~US$35 for 5 grams.

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  • $\begingroup$ Btw, what if there is lead in the paint, but not in pure form (I mean it would be a molecule with lead and something else)? Would potassium rhodizonate work as well to detect it? Or would lead even be toxic in that configuration? Also, how am I supposed to get rid of the vinegar-potassium rhodizonate mix after the test? Just discard it in the sink? $\endgroup$ – aspyct Jun 15 '15 at 12:16
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If it is made of Lead (II, IV) oxide, "Red Lead", it will dissolve in dilute solutions of $\ce{H2O2}$. Lead carbonate will dissolve in a hot solution of hydrogen peroxide and acetic acid. Lead chromate will form chrome red in a solution of $\ce{NaOH}$.

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