MicrobeHunter.com Microscopy Forum

Does anybody have an effective solution to dirty cover glasses and slides? It seems I always have to focus through finger prints and lines from cleaning cloths.

No need to pour dirt onto the slide. The default status of everything on Earth is dirty - cleaning is working against laws of Physics.

Here is a practical suggestion: always start with a low magnification - best of all, the 10X.
Bring the fine focus knob to its mid-range position. With the coarse focus knob, carefully focus on the rim of the coverslip. It is rather easy since it looks like either a straight line or a circular line.
Then, without changing focus, scan the slide until you find the region of interest. Continue with the fine focus knob until your object of interest is in sharp focus.
Assuming that your objectives are parfocal, switch to a higher magnification. When you do it, do not look through the eyepiece, rather observe the objective and slide from the side, so you clearly see the height of the objective front lens above the coverslip.
Resume watching through the eyepiece and correct the focus with the fine focus knob. I Assume that you stick with dry, no-immersion objectives. To switch a slide, switch first the objective back to the 10X.

If the above method works, neither a dirty coating nor oily finger prints will be required.

The problem I have is in cleaning the cover glass which is seriously impeding the contrast.

A general cleaning approach is to get a box of q tips and a bottle of isopropyl alcohol, wet one q tip and wipe, use another to soak it up before it can dry, throw each q tip away after one use.

Alcohol works better than soap?

Less likely to leave residue I would think. It will dissolve fingerprints easily and help mobilize dust.

I wash them with hand soap and then use an air duster and micro fiber cloth

I have to apologize for my previous response - I totally misunderstood the question. I thought you were seeking a liquid solution of dye or something else to pour on the cover slip and make a contrast area, a target for focusing , instead of focusing on fingermarks and such. My answer was formulated accordingly. Now I understand the question properly so again, my apology for a totally irrelevant answer.

To clean cover slips, IMO it is best to immerse them in dilute kitchen soap solution, rub them lightly between fingers to remove stains if any, then rinse with water (distilled water would be even better) and rub dry with a KimWipe. Ethyl alcohol rinse is a quick solution but not always sufficient. Isopropyl alcohol usually does a better job.

I actually really cut myself hand washing a slide once. Minor scratches with a cover glass once or twice. When I cut myself with the slide I was literally gushing blood I was like Jesus tap dancing christ. Wish I thought to look at it under the microscope.

DonSchaeffer wrote: ↑

Thu Jul 02, 2020 9:30 pm

Alcohol works better than soap?

No, not exactly. Ideally you want to triple-team your cover slips with a mixture of dish soap, water and alcohol. I like about 10-15% alcohol by volume, just a little squirt of dish soap and water. A spray bottle works pretty good here, or poke a needle hole into the top of a plastic water bottle and squeeze it to spray.

Real old-timers would use linen cloth that had been laundered at least twice. These days, I find liberal use of Kim wipes to be better as far as not leaving oily marks. Wash your hands real well first, you could use nitrile gloves but that's probably overkill. Every time you touch the slide use a fresh part of the wipe, so you'll need two or three per slide and another one or two per coverslip to do a really good job. Some folks even then like to store their clean slides in a tray of alcohol!

Oh, and if you ever want to test your skills with a real challenge, try cleaning up a dirty camera sensor.

Camera sensors aren't too bad if you just buy the kit and follow the instructions carefully. Unfortunately my budget won't let me do that every time I want to clean a lens or slide

Actually I did clean my camera sensor a few times. I use a blower.

The compressed air might damage the sensor with the high pressure

A squeeze blower.

The blower will sometimes clear eveeything up. If not the one time use pads and fluid do a good job to finish it off.

1. Throw them away.
2. Buy these: https://londonlaboquip.com/product/cove ... YAQAvD_BwE

An intelligent option and not even bad for the environment.

I think I found a solution: eyeglass cleaner and a microfiber cloth.

I have never had a problem with dirty cover glasses even ones that I have used. Soap water and kitchen towel to dry works for me.

I guess I'm not as particular as most of you.
I keep a small glass containing water and dish detergent. When I am finished with a slide, I put it into the glass, cover slip and all. When its time to clean, I rinse with hot water, rubbing slightly if necessary. Hand dry with a lint-free cotton dish towel. Even cover slips get dried by hand. Gentle handling has prevented cuts. At first I broke a couple of cover slips but not any more unless they're already slightly damaged.

The soaking in soapy water actually does most of the cleaning.

It's usually not too problematic unless you are doing darkfield and then every little speck, smudge and wipe mark shows up pretty starkly

An interesting topic,
I am not as experienced as you all and I am wondering if, or why, I should wipe dry ?

I only ever stand my reused washed** slides and cover slips on edge over absorbent paper to air dry.
What am I missing, what should I be looking for ?

I assumed that by wiping with something I was in danger of introducing unwanted "bits" ?

** variously with alcohol, dilute detergent, water etc. Sometimes with acetic acid (vinegar if it is at hand !) to remove stubborn haze out of the box or other deposits.

Mraster2 wrote: ↑

Sat Jul 04, 2020 6:18 pm

I am not as experienced as you all and I am wondering if, or why, I should wipe dry ?
I only ever stand my reused washed** slides and cover slips on edge over absorbent paper to air dry.
What am I missing, what should I be looking for ?
I assumed that by wiping with something I was in danger of introducing unwanted "bits"

If the final rinse of the coverslip is with a very pure liquid, such as distilled water (distilled. not boiled, not softened, not spring/mineral water), or pure alcohol, leaving them to dry as you mention is just fine. Especially if one holds the slides and slips by their rims.
If the final rinse is with a less pure liquid, for example vinegar (Not pure acetic acid, but vinegar), or even tap water, and the slides are then left to dry, dissolved involatile residues will remain on the slide. Whether or not they become a problem depends on how the slide is next used, namely, the illumination.
Wiping removes most of the liquid which contain those involatile solids, so wiping reduces the residue on the slide.

Thanks H.
"depends on how the slide is next used"
or by whom** it is next viewed !

I do have the means to use distilled water but not yet needed to**. Once upon a time I had access to RO but no longer, unless I buy some kit (which is a lot less expensive than it was )
My tap water was very hard (over 350ppm) but once boiled was very soft as it was nearly all bicarbs. Now though the Utility has taken to sodium substitution not sure how that will affect drying stains, hmmm, I'll think on that now that we have raised its ghost.

For clarification, the 'vinegar' is only for intermediate use (or first use for haze out of the box). Usually, over here, it is 'non-brewed condiment', but that is a mouthful

By standing on edge I am assuming that dissolved nonvolatiles would be carried down to the edge and confined there ? But I'll follow your prompt and watch out for illumination effects** in the future, thanks for the heads-up.
I am still experimenting with diy LED contraptions as my (gifted) old microscope came without.

I use empty paper egg cases to store my used slides and cover glasses. I stand them in the cups to dry.