Hey guys so quick question. 1 of my bottles of solvent I had done a evap check on had some oily residue. another was fine however I got them mixed up forgot wich was wich so I tested them again. Both came up clean this time. The difference was this time I didn't use heat to evap it. (the 1st time I did) I was on my way out the door so poured a bit on clean glass and left came back no residue on either! So my question I guess is If you use heat can there be to much heat maybe burning the solvent or something? I am going to test them both again to be sure but figured I would shoot the question to you guys and see what you think.

Maybe the first time round there was contamination on the glass surface that you didn't see beforehand?

I don't think so it looked clean. and the spot was exactly where the solvent was. maybe there was some super thin invisible layer there that the solvent brought out and made visible (if that is even possible I don't know) Ill have to just double and triple check everything I guess...I had a weird blue tint I made a post about after taking the plate out of the freezer the other day but that was a heptane solvent that came up clean but with some time that blue tint disapeered this bottle of solvent wasn't that heptane it was nap. so I don't know solvent stuff been leaving me confused lately

If in doubt - re-distill.
I would recommend to familiarize yourself with distillation procedure. It will help you to not only be sure of your solvent purity but to recover your solvents when they become dirty after extractions.
A distillation kit is available on Amazon for less than $40 and there are a lot of educational videos on Youtube. With some basic precautions it is fun and safe.

WOW I will say the thought crossed my mind but I thought the distilling equipment was a lot more money than that! Thanks for the advice deffinitly going to look into it!

Imho I would be very careful or rather wouldn't do that. This is potentially a very dangerous procedure and any mistake can end up in a disaster.
The good equipment is not all you may need. Very important is good knowledge and experience. If you are missing anything of that, you should at least consider not going this path.
I have all mentioned and prefer to buy new lab-grade bottle of solvent once it is needed (not very often) rather than distill. Not worth the risk when I am not a professional within lab-environment.

Did you pre-clean your evap surface? I'll also wipe with ipa before doing an evap test.

I have noticed "oily residues" from otherwise previously tested solvents that evaped clean and I have chalked it up to a oil that was applied to the glass during production (I've typically used the glass from a picture frame for a clean evap test)

pete666 I will deffinitly look into all the dangers before...I don't have lab experience but have worked with dangerous chemicals for many more reasons than this and things at VERY high or VERY low temps. even have a space outside in a metal shed built for things that may be a fire risk! I will deffinitly look into things first!

dreadedshaman thank you as well a picture frame would be a perfect idea ill clean one off really good and double check everything to be sure

Unless you're willing to discard your dirty solvents into the environment, a distillation apparatus is a must. It will allow you to purify your solvents, to save on them and be more Eco-friendly.

Do not get discouraged. It is very basic procedure. With the right equipment and simple precautions you will be fine. Watch a dozen videos. Make notes. Ask questions. Make sure you understand how it works.

Get The Organic Chem Lab Survival Manual: A Student's Guide to Techniques, 9th Edition
by James W. Zubrick. I believe it has been uploaded here. Let me know if you could not find it. There is a lot of useful information about safety (Ch.1), lab glassware (Ch.4), sources of heat (Ch.17) and distillation (Ch.19). No need to read it through. Read the relevant parts.

Of course the $40 apparatus from Amazon is not enough. You will need a source of heat. Do not use open flame. A hotplate would do but a cheap heating mantle is much better. You'll need a pump to run cold water through your condenser and a lab stand with several clamps. Do not forget to use boiling stones. Pieces of broken not glazed earthenware would do. Well, you will find all these advises and more in the videos.

To get some experience you may try some very simple and safe distillations like distilling alcohol from a cheap wine. Do some reading about properties of the solvent you are planning to distill. Some may be really dangerous, like diethyl ether, but we do not use it around here.

Ask chemists around here. I am sure they'll agree that distillation is not a rocket science.

Don't worry I wasn't discouraged just cautious I don't have experience with lab stuff. But well I work well in dangerous situations if that makes sense haha....started making custom knives years ago wich lead to all sorts of metal work like heat treating steel with very high temps and very low temps (liquid nitrogen) making Damascus steel wich lead to using "cans" of powdered steel and some other materials that when put in a forge if heated wrong can turn into a bomb quick. So yeh no lab type experience but I understand and respect working in difficult and dangerous situations.

And trickster you brought up a good point about not discarding solvents into the environment...that really isn't good....I talked to a guys that would litterly burn them cause he didn't want to pour them out somewhere but he was ok with letting it into the air for somereason ?!?! I am going to start some research and trickster I might shoot ya a pm if I have any questions if that's cool with you.

Always Distill.

I believe distillation is a basic human skill, like changing a tire that people should be aware of and practice. If the "average joe" had simple distillation knowledge, we would be on a much faster track to being eco-friendly and sustainable as the human race should be.

It's easy, simple, and saves you money. But more importantly, distilling your own resources gives you the PEACE OF MIND available from modern chemistry.

Light and Love and Travel Well.