Evaporation Question

[teonanactl]

Swim recently did an evaporation test on some vm&p naptha recommended here and found that it left some kind of residue. Enough naptha was poured into the bottom of a 5 x 7 inch pyrex dish that the bottom was evenly covered in a thin layer. Upon 1rst inspection the dish looked perfectly clean, however when held to the light 2 very faint rings were observed. They appear to be evaporation rings but they are separate and there is only 2 of them. The residue is !00% clear and cannot be seen normally. The dish must be held at exactly the right angle so the reflection of the light shows, otherwise you would never see it. The residue could be scraped off with a card, but it just seemed to disappear and could be neither be collected or felt in any way. Swim is already pretty sure that this naptha is no good to use but just wanted to make sure.

 

[Spock's Brain]

It sounds like, to swim, you might not have be anything to worry about. Maybe the solvent collected some moisture, and that's what's showing up, or some condensation from the air during evaporation. You could attempt to evap a larger amount of the solvent in question if your really concerned about it. Of course, you want to avoid using a solvent that leaves behind it's own residue, but when it's all said and done with, the process is also going to ultimately yield some additional oils and substances in addition to the main substance in question. You could go back to your hardware store an tell them you need some napth that's absolutely clean drying bacause your producing exquisitely fine art using expensive paints that you don't want to mess up. Use VMP and/or use Bestine. If you really want to be prescise, you could use a piece of mirror instead of a glass tray to evap it on, to see what's left behind, if anything...

 

[rellik]

ive encountered the same, it dosnt happen all the time either with the same naptha batch

considering all the junk that we inhale throughout our daily lives, personally i dont worry much about that small faint residue anymore. its still better to be safe than sorry though

 

[endlessness]

Dont evap on your final step, do freeze precipitation, and you´ll be fine

 

[Spock's Brain]

ive encountered the same, it dosnt happen all the time either with the same naptha batch

considering all the junk that we inhale throughout our daily lives, personally i dont worry much about that small faint residue anymore. its still better to be safe than sorry though

yeh, thats what I was trying to say... exactly!