TL;DR — Neither a worn-out cellulose round nor a worn-out silicone pad belongs in your recycling bin. The difference shows up after the bin: in the same 2023 seawater study, regenerated cellulose fully biodegraded in about 35 days while oil-based fibers were unchanged after 428 days. But "compostable" is a claim about conditions, not a property of a material — LastObject names no composting standard behind its own claim, and silicone wins the disinfection criterion under California salon rules.
A worn-out reusable makeup pad goes in the same place whether it's cellulose or silicone — the trash — but the two materials do not behave the same once they get there, and somebody has measured both. In a 2023 Scripps Institution of Oceanography study, natural and regenerated cellulose fibers biodegraded completely in seawater in roughly 35 days, while PLA and oil-based fibers were essentially unchanged after 428 days. Everything else in this comparison is conditions — and conditions are where most sustainability copy quietly cheats.
Figure 1 — End-of-life routes: cellulose round vs. silicone or TPE pad
This article is published by LastObject, which makes one of the two products being compared. So it is not a hit piece on silicone. It's an attempt to say exactly which criterion each material wins, and to name the ones we lose.
The criteria, named before the verdict
- Curbside recycling. Can the spent item go in the household recycling bin?
- Standards behind the disposal claim. Is there a named test standard, and under which conditions?
- Measured biodegradation outcome. When both materials went into the same test, what came out?
- Disinfection. Can the item be sanitized rather than replaced?
- End-of-life detection. How do you know it's spent?
We win 3. We tie on 1 — the answer is no for both. We lose 4 on a written regulation. On 2 and 5, nobody wins: neither material has a named standard behind its disposal claim, and neither has a published, independently tested cycle count. One win, one loss, three draws is the honest scoreline.
Note what criterion 3 is and isn't. It is not "has anyone measured it?" — both materials were measured, in the same study, so that question is a draw and would have been a rigged win for us if we'd scored it. Criterion 3 is the outcome of that measurement, which is a test the cellulose could have failed and didn't. The single win is the one that matters, but only if your disposal route is real.
The short version
| End-of-life question | Cellulose round (30% cotton / 70% lyocell) | Silicone or TPE pad |
|---|---|---|
| Household recycling bin | No | No |
| Resin identification code | None — it is a textile | Typically none, or code 7 "other" |
| Composting route | Claimed; LastObject says home-compostable, no compostability standard or test house named | None claimed |
| Measured biodegradation outcome (same 2023 seawater study) | Cellulose fibers: complete breakdown in ~35 days, CO₂-measured | Oil-based fibers: unchanged at 428 days |
| Named in California salon rules as non-disinfectable | The rule names "cotton pads"; applying it to a 70% lyocell round is a reading, not a citation | Not named |
| Documented cycle count | LastObject's own figure: ~250 washes per pad | Not published in any source I could find |
| First visible failure | Permanent discoloration, thinning, fraying | Cracks, holes, surface tackiness |
"Compostable" is a claim about conditions, not about a material
This is the sentence I most want you to keep. Composting standards are defined by temperature, time and residue, not by what the thing is made of. EN 13432 requires at least 90% biodegradation within six months and 90% of the material passing a 2 mm sieve after twelve weeks, and the ISO 14855 test that underpins it runs at 58 °C. That is intensive industrial composting. Your garden heap does not reach 58 °C, and a standard written for that temperature says nothing about what happens in a bin behind your shed.
So here is our own claim, handled the way I'd want a competitor to handle it. LastObject's refill page states that the rounds are home-compostable when fully spent, and it names no compostability certification, no test standard and no test house for that claim. Until it does, treat "home-compostable" as our claim, not as a verified result.
The same page does name a certification, in the same breath as the compost claim: "OEKO-TEX certified, machine-washable to 60°C, compostable at end of life." That is worth being precise about, because it is our page. OEKO-TEX is a textile certification — it concerns tested substances in the fabric. It is not a composting standard, it does not test biodegradation, and it says nothing about whether a round breaks down in a garden heap. Reading it as support for the compost claim would be exactly the substitution this article is arguing against.
Note also what EN 13432 is not. It is an industrial composting standard, which makes it the wrong yardstick for a home-compost claim in either direction — holding our claim up against it would be an unfair test, and passing it would not prove the home case either. The honest statement is narrower and worse for us: no compostability test of any kind has been named. LastObject separately describes the rounds as free from synthetic dyes and chemical treatments, but that is a description of the material, not a certificate covering how it breaks down.
The Scripps result is the strongest thing on our side of the table, and it also needs its caveat: it measured seawater, not compost and not landfill, and one of its co-authors is affiliated with the largest producer of lyocell fiber, though the authors themselves declared no competing interests. It tells you the polymer mineralizes when microbes get at it. It does not tell you a round dissolves in your compost bin in five weeks.
Silicone and TPE have no equivalent claim at all — not a weaker one, none. That is the actual gap, and it is a gap in claims, not in verified results.
Neither of these belongs in your recycling bin
This is the part that costs people nothing to get right and costs recycling programs real money when they get it wrong.
The triangle on a plastic product is a material identification mark. ASTM's own standard states plainly that resin identification codes are not recycle codes, and that carrying one does not imply any system exists to process the item. Elastomers like silicone and TPE usually carry no code at all, or fall into code 7, "other" — the residual bucket.
Size finishes the argument for the silicone pad. Field sampling at US sorting facilities found that small-format items are screened out during sorting and end up in landfills and incinerators, with the threshold set by the Association of Plastic Recyclers at under two inches in at least two dimensions and larger items lost in practice too. A pad of a few centimetres sits right in that loss zone. That report covers rigid small-format packaging in materials recovery facilities, so it does not describe our round at all — a textile never enters that stream in the first place. Which is another way of arriving at the same place: the recycling bin is not the route for either one.
So: cellulose round goes to compost if your setup genuinely composts textiles, otherwise trash. Silicone pad goes to trash. Putting either in the recycling bin is wish-cycling — it doesn't get recycled, and it degrades the quality of the load it rode in on.
Knowing when a pad is actually spent
There is no independently tested cycle count for either material, and I'd rather say that than invent one.
The closest thing to a rule comes from reprocessing research on reusable medical devices, which concluded that the number of cycles at which a device should no longer be used cannot be predetermined, and that the changes the researchers observed were predominantly discoloration. Those were metal surgical instruments in validated washer-disinfectors, not textiles in a bathroom sink; the inspection criteria they worked from also covered rust, pitting, cracks and function, and the authors were employed by a device manufacturer. But the principle transfers cleanly: you inspect, you don't count.
For a cellulose round, that means looking for discoloration that survives a wash, areas thinned enough to see light through, a fraying edge, and a surface that drags instead of glides. LastObject rates each pad at approximately 250 wash cycles and the seven-pad set at roughly 1,750 single-use rounds replaced over its lifetime — note that this is 7 × 250, our own arithmetic, not an independent durability test.
For silicone, the documented failure mode is different in kind. Materials research on silicone rubber under combined heat, oxygen, mechanical stress and chemical exposure found that the degradation is not a simple superposition of those factors and that cracks and holes appear on the surface. That study looked at seals in a marine atmosphere at 110–150 °C, not pads on a bathroom shelf — but cracks, holes and tackiness are what you're looking for, and a cracked surface is harder to clean than an intact one.
Where silicone honestly wins
On the disinfection criterion, we lose on a written rule, not on an argument. California's cosmetology regulations name cotton pads and sponges among the tools that cannot be disinfected and must be thrown away after a single client. Silicone is not on that list; a hard, non-porous surface is the category those rules permit to be cleaned and reused.
Two limits on that, both in our favor, and neither big enough to change the verdict. The rule governs professionals serving multiple clients, not what you may reuse on your own face. And it names "cotton pads" — a round that is 30% cotton and 70% lyocell is not literally the listed item, so applying the rule here is a reading rather than a citation. But the material logic behind it is real: a porous fiber absorbs; a non-porous surface doesn't. We take the loss.
And on lifespan: I could not find a published head-to-head comparing how long a silicone round survives versus a textile one. Silicone may well outlast us. Nobody has run the test, and until somebody does, treat any claim in either direction — including ours — as marketing.
When a LastRound is the wrong pad
- Acetone and nail polish. LastObject describes the rounds as working with water-based products — micellar water, toner, makeup remover, serum, exfoliant — and its refill page states plainly: "Do not use bleach or harsh solvents." Aggressive solvents are outside that description and outside the brand's own care instruction. Use something disposable.
- Compromised skin. Active skin infection, or broken or open skin, is outside what any product page can assess. That question belongs with a clinician rather than with a brand.
- Acne-prone skin. The American Academy of Dermatology's published guidance describes applying cleanser with the fingertips, noting that scrubbing with washcloths, sponges and other tools can irritate the skin. That guidance points away from any pad, ours included.
- Travel with no laundry access. A reusable system you can't wash is just damp cotton in a bag.
- Precision work. A round is a broad-surface tool. Cleaning up a smudged wing is a different job for a different shape of tool.
- Wash debt. A disposable pad has no maintenance. Ours has a mesh bag, the brand's own instruction to rinse or wash after each use, a 60 °C cycle, a drying step, and a stated care instruction to skip fabric softener, which LastObject says coats the fibres and reduces absorption. If that friction means you'll skip washing, buy the disposable.
Closing the loop
The end-of-life decision that actually matters financially is the refill, not the set. At LastObject's US store on 18 August 2026, a LastRound set costs $16.00 and a refill of rounds costs $9.00 — the laundry bag stays, so a spent set doesn't mean a replaced system.
That's the conditional verdict. If your disposal route is real — municipal organics that accept textiles, or a compost setup you actually run — cellulose gives you an end-of-life route that silicone does not have and does not claim. If your route is the trash can either way, the material difference at end of life is smaller than the packaging suggests, and you should choose on hygiene and handling instead. Both of those are honest answers. They're just not the same answer.
