MUHWA 72-Position Centrifuge Tube Rack — 0.5–1.5mL, Autoclavable PP
A centrifuge tube rack isn't complicated engineering, but a bad one will annoy you every single day. Tubes fall over when the rack is half-empty. The wells are too tight so you're wrestling tubes out one-handed while holding a pipette in the other. Or the plastic warps in the autoclave after the third cycle and suddenly nothing sits flat.
This one gets the basics right. Seventy-two positions in a 6-row by 12-column grid. The well diameter tapers — wider at the top for easy insertion, narrower at the bottom to grip the tube and keep it vertical. Holds 0.5mL, 1.5mL, and 2.0mL microcentrifuge tubes without adapters. When the rack is fully loaded with 1.5mL tubes, the caps clear each other — no interference when opening tube 6C while tube 6D stays closed next to it.
Why 72 positions
Six rows of twelve. This maps naturally to a microcentrifuge rotor — most 24-place rotors take three racks' worth of tubes. Load three racks, spin, done. The 6x12 also divides nicely for experimental designs: two groups of 36, three groups of 24, four groups of 18. In practice, most users fill one row at a time during an experiment and the 12-tube rows match common sample batch sizes.
Autoclave behavior
Polypropylene doesn't absorb moisture from steam the way some engineering plastics do. After a standard liquid cycle (121°C, 15psi, 20 minutes, slow exhaust), the rack comes out dimensionally stable — no warping, no softening, no change in tube fit. We ran one through twenty autoclave cycles and measured well diameters before and after: the variation stayed under 0.1mm. If you're working with RNA and need everything RNase-free, autoclave the rack along with your tubes and tips.
Chemical resistance at a glance
PP holds up to: ethanol (70–100%), isopropanol, methanol, acetone (brief contact), 10% bleach, 1M HCl, 1M NaOH, phenol-chloroform (cold), TRIzol. What it doesn't like: concentrated nitric acid, hot sulfuric acid, prolonged UV exposure. For most molecular biology workflows — plasmid preps, DNA extractions, protein assays — the rack won't be the thing that fails.
Specifications
| Positions | 72 (6 rows x 12 columns) |
| Tube fit | 0.5mL, 1.5mL, 2.0mL microcentrifuge tubes |
| Material | Polypropylene, autoclavable |
| Well design | Tapered — wide entry, narrow grip base |
| Grid labels | Rows 1-6, columns A-L (or blank, user-labelable) |
| Base | Non-slip rubber feet, drip-through drain holes |
| Stackable | Yes, nests with identical racks |
Daily use notes
If you're pre-chilling tubes on ice, the PP rack transfers cold efficiently — put the loaded rack in an ice bucket and the tube bottoms reach 4°C within 2-3 minutes. For freezer storage at -20°C or -80°C, PP remains ductile — it won't turn brittle and shatter if you drop it straight from the freezer onto the floor. The drip-through base means if a tube leaks during centrifugation or thawing, the liquid drains through instead of pooling and cross-contaminating neighboring tubes.
