Short answer: An export footwear factory ran a same-batch side-by-side trial of A505 anti-mold chips vs C304 anti-mold bags. Result: A505 outperformed C304 overall, with a clearer advantage in harsh conditions (large boot boxes, high RH, long-route simulation). C304 remained adequate for standard boxes and budget-first low-risk packs. Choice depends on risk tier and budget.
| Client type | Footwear OEM factory |
|---|---|
| Products | Leather dress shoes (standard boxes) + suede boots (large boxes) |
| Purpose | Decide A505 vs C304 by shoe type / box size |
| Test condition | Climate chamber, 28 days, 8 mold species |
| A505 groups | 1 chip / standard box; 1 chip / large boot box |
| C304 groups | 1 bag / standard box; 1 bag / large boot box |
| Result | A505: Grade 0 in all groups at day 28. C304: Grade 0 in standard boxes; large boot boxes showed faint edge discoloration from day 21 |
Why run the trial
The plant had standardized on C304 for cost. Brand auditors asked whether tall / suede boots needed an upgrade to A505. Bester recommended a controlled comparison instead of a price-list decision.
Test method
Groups
| Group | Shoe | Box volume | Insert | Pairs |
|---|---|---|---|---|
| A1 | Leather dress shoe | Standard (~3L) | A505 ×1 | 10 |
| A2 | Leather dress shoe | Standard (~3L) | C304 ×1 | 10 |
| B1 | Suede tall boot | Large (~7L) | A505 ×1 | 10 |
| B2 | Suede tall boot | Large (~7L) | C304 ×1 | 10 |
Chamber settings
- Temperature: 55°C day / 28°C night
- Humidity: 85% RH
- Duration: 28 days
- Checks: day 7 / 14 / 21 / 28
Results
| Group | Day 7 | Day 14 | Day 21 | Day 28 | Mold grade |
|---|---|---|---|---|---|
| A1 (standard + A505) | None | None | None | None | Grade 0 |
| A2 (standard + C304) | None | None | None | None | Grade 0 |
| B1 (large + A505) | None | None | None | None | Grade 0 |
| B2 (large + C304) | None | None | Faint edge discoloration* | No visible mold | Grade 0 (edge reaction) |
*Note: B2 (C304 + large boot box) showed faint edge discoloration on the bag by day 21 — a coverage-boundary signal in large volume + high RH, not visible mold. On longer / harsher ocean lanes that margin may be exceeded.
Selection guide
| Scenario | Recommend | Why |
|---|---|---|
| High RH / long route / high-moisture materials | A505 chip | Higher active concentration, more stable coverage |
| Large boot boxes (>4L) | A505 chip | A505 outperformed C304 in large-volume groups |
| Standard box + short transit | C304 bag | Adequate under standard conditions; lower cost |
| Budget-first + low risk | C304 bag | Standard materials, short routes, non-monsoon |
| Brand audit / high-spec POs | A505 chip | Stronger safety margin and trial evidence |
Next step for buyers: Pick the SKU for your risk tier, then request free samples for a line trial.
A505 product page · C304 product page · Anti mould bag hub ·
Factory decision
The plant upgraded the main line to A505 (1 chip per standard box; 1 chip per large boot box). C304 remains for budget-sensitive, short-route, standard-material low-risk orders. Both SKUs share the same mold-growth report family (same active chemistry class; A505 at higher concentration).
Limitations
- Chamber ≠ ocean — Steady high RH/heat can be harsher than average voyages, but real voyages have more temperature swings.
- Material-specific — Trial used leather and suede; other materials may differ.
- Seal quality matters — Boxes were well sealed; weak seals reduce any insert’s effect.
- Edge discoloration ≠ mold — Day-21 B2 signal is a coverage warning, not mycelium. Prefer A505 for high-spec large boxes.
Relevant test data
According to Guangdong Detection Center of Microbiology Report No. 2025FM00761R01D (DA/T 26-2000, issued 2025-02-26) — Grade 0 after 28 days, 8 mold species, on paper/cloth/leather. A505 and C304 share the same active composition family; A505 is the higher-concentration chip format.
SGS REACH CANAF26001423003 — 251 + 4 potential SVHCs, all not detected. SGS DMF CANAF26001423001 — not detected. Details: Testing & Compliance Center.
FAQ
What is the difference between A505 chip and C304 bag?
Same vapor-phase chemistry class; A505 is higher concentration and more stable in large boxes / harsh humidity. C304 is lower cost for standard low-risk packs. Overview: anti mould bag hub.
When should a factory choose A505 vs C304?
High-risk export → A505. Standard short-route / budget-first → C304. If unsure, lock A505 and .
Is A505 much more expensive than C304?
Slightly higher unit price; one mold claim usually dwarfs the gap. Ask procurement questions in the Buyer FAQ.
Can one factory mix A505 and C304?
Yes — by SOP per risk tier, not mixed randomly in one PO. See also Case 02 (suede trial).
Sources and further reading
For factories & exporters
Home mold cleaning is not the same as export packing mold control. If you run a shoe factory or brand program, use vapor-phase anti-mold inserts (not silica gel alone) before sealing boxes.
Anti mould bag hub · A505 chip · C304 bag · A505 vs C304 trial · Why silica fails · Buyer FAQ ·