A slide is anything thin and clear enough for light to pass through, set on glass under a cover slip. Most specimens need either a drop of water or nothing at all.
Lowering the cover slip at an angle keeps air bubbles out.
Wet mount
Use a wet mount for anything living, anything soft, and anything that is already a liquid.
Put a small drop of water on a clean slide. For pond water, yogurt or honey, skip the water and use a drop of the sample itself.
Add the specimen with a toothpick or forceps, touching it into the drop so it lets go.
Lower a cover slip. Rest one edge on the slide beside the drop and let the slip fall slowly, which pushes air out ahead of it.
Start at low power, find your specimen, then move up.
Hair, feathers, a fleck of newsprint, a thread of cloth, a scrap of leaf or an insect wing need no liquid at all. Place it on the slide, lower a cover slip over it and look.
Thick specimens rock under a flat cover slip. A concavity slide, with a shallow well ground into the glass, holds them still.
Add a stain for contrast
Most cells are nearly transparent, so a stain makes the parts show. Methylene blue colors nuclei, which makes cheek cells and onion skin easy to read.
Put a drop of stain at one edge of the cover slip and touch a scrap of paper towel to the opposite edge. The paper draws the stain under the slip and across the specimen.
Vital stains are made for staining living cells.
Which stain for which specimen
Stain
What it shows
Good for
Methylene blue
Nuclei, in blue
Cheek cells, onion skin
Iodine
Nuclei, more clearly than no stain
Onion skin
Ink, after alcohol
Nuclei, with no stain kit
Onion skin
Acetic orcein
DNA, in reddish purple
Onion nuclei, after fixing in ethanol
Staining onion cells
Swift Microscope World stains onion skin with iodine or methylene blue to make the nuclei stand out.
For the DNA itself, Swift uses acetic orcein. The tissue is fixed in ethanol first, and the stain turns DNA-rich nuclei reddish purple while the cell walls stay pale.
With no stain kit at all, Microbehunter stains onion nuclei with ordinary ink. Alcohol goes on first to draw water out of the cells, then ink, then water to rinse off the excess.
Lower the stage first, so the slide goes in well below the objectives.
Seat the slide cover slip up. On a mechanical stage, push the holder's lever open, slide the glass in flush against the back edge and let the lever close on it. A plain stage holds the slide under its two clips.
Center the specimen under the objective with the stage knobs. The image moves the opposite way to the slide.
Start on the lowest power objective, usually 4X, which shows the widest view.
Raise the stage slowly with the coarse focus knob. When shapes appear, switch to the fine focus knob until the detail is sharp.
Turn to 10X, then 40X, watching from the side as each objective swings in so it never touches the slide. Touch up the fine focus and the light at each step.
Things worth a first look
Onion skin, peeled thin from inside one layer, with a drop of methylene blue.
Pond water, straight from the jar, as a wet mount.
Yogurt, a tiny smear in water, for the bacteria that make it.
Your own hair next to a pet's, as dry mounts side by side.
Slide-making supplies on Amazon
Affiliate links. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you.
Blank slides
AmScope BS-50P-100S-22 blank slides and cover slips
50 pre-cleaned glass slides, 25.4 x 76.2 mm, with 100 square glass cover slips, 22 x 22 mm and 0.15 mm thick.
Peel a thin layer, mount it in a drop of water, and draw iodine or methylene blue under the cover slip with a scrap of paper towel. Microbehunter's no-kit method uses alcohol, then ink, then a water rinse.
Iodine works on onion skin, and Swift Microscope World uses both to show nuclei. Microbehunter stains onion nuclei with ink after an alcohol soak.
Acetic orcein. Swift Microscope World applies it after fixing the tissue in ethanol, and it colors DNA-rich nuclei reddish purple.
Lower the stage, seat the slide cover slip up in the stage holder or under the clips, and center the specimen. Start on the 4X objective, raise the stage with the coarse knob until shapes appear, then sharpen with the fine knob before moving to 10X and 40X.
Paint clear nail polish around the edge of the cover slip. The polish seals the edge and slows drying.
Put a drop of water on the slide, add the specimen, and lower a cover slip from one edge so it pushes the air out ahead of it.
