Before getting a more or less clean ACS heptane (still leaves a faint water mark/ring) I got myself a couple of liters of other random naphtas.

Was thinking on using them as fireplace lighter fluid, but thought that maybe could give them a better use by pulling with them and then re-x'ing with the heptane.

Would this work to have a clean final product? Or the stuff in the naphta will not be removed by heptane? or a further water/carbon wash?

Pull and re-x should help if you really don't have the option of distilling your solvent. You could try treating the heptane with carbon before use, although it's worth bearing in mind that the faint mark left from its evap test could have been residues that were already present on the testing surface. One way around this is to wipe the testing surface with a clean cloth moistened with a little of the solvent to be tested.

I was wondering how you plan to carry out the heptane re-x. What would each of your steps be?

The Heptane is ok. It sometimes leaves the faint watermark and sometimes not. I'm pretty sure that it has something to do with the air humidity at the time of the test. Read through other forums and some people confirm that a faint watermark is often seen in good heptane.

The question is if the heptane re-x would help cleaning a product pulled with a not so clean naphta. In other words, if it would mix with the higher hydrocarbons present in the product and take them with it while leaving the dmt crystalized.

Yes, the whole point of recrystallisation is to remove trace impurities, at the cost of some of the yield. I wanted to check that you understood the principles of it, particularly the point that it does not consist of evaporating the heptane.

The oily residues from the naphtha will, with a high degree of certainty, be soluble in the heptane. If they aren't they'll be left behind and you can decant or filter off - just don't be fooled by any oily DMT oligomers at this point!

No, I think that fully evaporating a solvent would definitely leave whatever the solvent had in it with the final product!

If I understand this well, then performing the initial pull with a naphta that doesn't pass the evap test, and then cleaning the product with an heptane re-x (plus probably an activated charcoal wash + filtration) would give a product of a resulting purity similar to an extraction done with the heptane alone. With slightly less product, but probably more than what would been pulled out in the latter case.

Is this correct?

It's hard to say one way or the other about the yield, but you'll certainly use less heptane if you save it for the re-x! I did get very good yields with some BBQ lighting fluid way back in the mists of time so I'd be inclined to be optimistic