MUHWA EVA Foam Float Rack — 16 Holes, Water Bath, Pink
This is the foam version, not the hard plastic one. It's made from closed-cell EVA — the same kind of foam used in pool floats and life jackets, just denser and autoclavable. 16 holes, takes 0.2mL PCR tubes, 0.5mL, and 1.5mL tubes interchangeably. Floats stably even with a full load. Pink — you won't forget it in the water bath when cleanup time comes. Six racks per pack.
We make a plastic float rack too (polypropylene, round, blue, 26 holes). The plastic version is better if you're working with solvents or oil baths. The foam version is lighter, naturally buoyant, and costs less — good for teaching labs and routine molecular biology where you just need something that floats in water and goes through the autoclave. If you jab the foam with forceps, it won't sink. If a hollow plastic float cracks, game over — it fills with water and drops to the bottom.
What It Fits
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| Holes | 16 (4 x 4 grid) |
| Tube sizes | 0.2mL PCR, 0.5mL, 1.5mL — all in the same rack |
| Material | Closed-cell EVA foam |
| Buoyancy | Inherent — no air chambers to crack |
| Autoclavable | 121 degrees C, 15 psi, 20 min |
| Water absorption | Negligible |
| Color | Pink |
| Pack size | 6 racks |
What It Can and Can't Handle
Things it handles fine: 37 degrees C water baths for restriction digests. 42 degrees C for heat-shock transformation. 55-65 degrees C for reverse transcription and probe hybridization. 95 degrees C for PCR — the foam doesn't melt or deform at boiling-water temperatures. Autoclaving at 121 degrees C. Ethanol, isopropanol — brief contact is fine. Soap and water. Bleach wipes.
Things to avoid: Don't leave it soaking in organic solvents overnight. Don't use it in an oil bath — the foam can absorb mineral oil over time and lose some buoyancy. If you're working with phenol/chloroform extractions, keep the rack out of the solvent phase. These are water bath floats, not chemical-resistant workstations. For solvent-heavy work, use our polypropylene float rack instead.
Questions We Get
Does the foam absorb water over time?
No — that's the "closed-cell" part. Each cell in the EVA foam is sealed, not interconnected like a sponge. Water sits on the surface. After a year of daily water bath use, same buoyancy, same weight. If you leave it submerged for weeks, some moisture might work into surface pores, but it dries out completely overnight on the bench.
Can I autoclave it?
Yes. 121 degrees C, standard cycle. The pink color may fade slightly after 50-plus cycles but the foam holds its shape and buoyancy. Replace when you see visible cracking or crumbling at the edges — usually after a couple hundred cycles in a busy lab.
Sixteen holes seems small — why not more?
The foam needs enough material between holes to maintain rigidity. At 16 holes, each tube has solid foam around it — they don't touch each other, they don't rattle, and the rack doesn't flex when you pick it up fully loaded. If you need more capacity, get a second rack. At six per pack, that's 96 tubes floating at once across the set.
How is this different from the plastic float rack?
The plastic version (round, blue, 26 holes + 8 holes) is made of polypropylene and uses hollow chambers for buoyancy. It's more chemical-resistant but pricier and heavier. The foam version costs less, weighs less, and floats by material property rather than trapped air. Both are autoclavable. Choose plastic if solvents are frequently involved; choose foam for cost-sensitive setups, teaching labs, and pure water bath work.
Can I label these?
Permanent marker writes on the foam surface. After a few water bath sessions the ink will fade. Better approach: wrap a strip of colored lab tape around one edge of the rack — red for 37 degrees C, blue for 42 degrees C, etc. The tape stays put and doesn't come off in the water bath.
Real Lab Use Cases
Heat-shock transformation: Sixteen tubes of competent cells, 42 degrees C water bath, 45-90 seconds. The foam holds the tubes at exactly the right depth — not too deep (water gets into the cap threads), not too shallow (cells don't heat evenly). Pink rack is easy to spot when you're rushing the ice bucket to the water bath and back.
Restriction digests at 37 degrees C: Load your enzyme + DNA + buffer mixes, pop the rack in the 37 degrees C bath, set a timer. No need for floating tube holders or improvised styrofoam. Sixteen reactions per rack — that's a full cloning project worth of digests.
RT-PCR setup: 42-55 degrees C reverse transcription step. The rack holds 0.2mL PCR strip tubes as well as individual tubes, so you can run 16 cDNA synthesis reactions in parallel.
Thawing frozen aliquots: Instead of holding a tube between your fingers under the tap or leaving it rolling around in a beaker of warm water, drop the frozen tube in the rack and float the whole thing. The tube thaws evenly, stays upright, and you don't have to stand there holding it.
