MUHWA 24x24mm Glass Cover Slips — Number 1.5, Borosilicate, 200/Pack
Twenty-four by twenty-four millimeters, square, 0.13 to 0.17mm thick. That's the cover slip you reach for when you're mounting a standard tissue section or a fluorescence-labeled sample and you need the whole 24x24mm area covered. Two hundred per box, pre-cleaned.
Number 1.5 thickness matters more than most people think. High-NA objectives — your 40x/1.3 oil, 60x/1.4 oil, 100x/1.4 oil — are designed with a 0.17mm coverslip in the optical path. The objective corrects for spherical aberration assuming exactly that thickness. Use a number 1 (0.13-0.16mm) or number 2 (0.17-0.25mm) and your image is soft at the edges. If your lab standard is number 1.5 across all objectives, you get consistent correction whether you're on the 20x dry or the 100x oil.
Borosilicate glass, not the cheaper soda-lime. The difference shows up in fluorescence. Soda-lime has enough iron and other impurities that it autofluoresces — a dull green glow under UV and blue excitation. If you image DAPI, FITC, GFP, or any fluorophore in the 350-550nm excitation range, that background autofluorescence sits right on top of your signal. Borosilicate is cleaner — lower background, better signal-to-noise. For brightfield histology (H and E, IHC with DAB), the glass type doesn't matter optically, but borosilicate is flatter and less prone to thickness variation across the slip.
Using Them
Pick one up by the edges — fingerprints on the surface show up under the microscope. If you need optical-grade cleanliness (confocal, TIRF, super-resolution), dip in 70 percent ethanol and air-dry on a lint-free wipe immediately before mounting. Don't wipe — wiping generates static that attracts dust. Let the ethanol evaporate.
For aqueous mounting media: place a drop of mounting medium on your stained section, lower the coverslip at an angle with forceps, and let it settle slowly to push out bubbles. If bubbles are trapped, gently press with the wooden end of a cotton swab. Don't press with metal forceps — you'll crack the slip.
For organic mounting media (Permount, DPX, Eukitt): same technique, but work faster. Xylene-based mounting media start to thicken within 30-60 seconds of exposure to air. Have your coverslip ready before you apply the medium.
Specs
| |
|---|
| Dimensions | 24 x 24mm, square |
| Thickness | Number 1.5 (0.13-0.17mm) |
| Glass type | Borosilicate |
| Pieces per pack | 200 |
| Pre-cleaned | Yes |
| Compatible applications | Brightfield, phase contrast, DIC, fluorescence (widefield and confocal), IHC, ISH |
FAQ
Number 1 vs 1.5 vs 2 — which do I need?
For any objective with NA above 0.75: number 1.5. That covers essentially all 40x dry, 40x oil, 60x oil, and 100x oil objectives on research microscopes. Number 1 is for low-NA objectives (10x, 20x) where spherical aberration is less critical. Number 2 is mainly for specialized thick-sample applications. If you only stock one thickness, make it 1.5.
My fluorescence images have a green haze in the background. Is it the coverslip?
If you're using soda-lime coverslips and imaging in the FITC/GFP channel (450-490nm excitation), yes — soda-lime autofluorescence sits in the green. Switch to borosilicate. If the background is uniform across the field and present even without a sample, it's probably the glass. If the background is patchy or associated with the tissue, it's your staining or mounting medium.
Can I use these for live-cell imaging chambers?
These are single-use coverslips for fixed-sample mounting. For live-cell imaging, you want coverslip-bottom dishes or chambered coverglasses where cells are cultured directly on the glass. These 24x24mm slips are too thick and not treated for cell adhesion.
