Three small parts, three different engineering problems
A sink strainer has to fit a hole. A colander has to drain fast without letting food through. A dish rack has to hold 15 kg of wet plates and get the water into the sink instead of onto the worktop.
They are bought together, quoted together and shipped together, which is why they are often specified together — and why the specification is usually wrong for at least one of them.
Strainers: fit first, material second
The drain opening is the constraint. A 3½ inch (89 mm) opening is the common standard in North America; European sinks vary more, and 80 mm and 84 mm baskets are both found in the market. Never assume — ask the buyer to measure the opening, or supply a basket with a flange wide enough to bridge the range.
| Parameter | Typical value | Note |
|---|---|---|
| Basket outside diameter | 75–85 mm | Must clear the opening with 1–2 mm each side |
| Flange diameter | 95–115 mm | Wider flange covers oversized openings |
| Basket depth | 25–40 mm | Deeper catches more, but blocks the trap less |
| Perforation | 2–3 mm round, or 1.5 × 8 mm slot | Round is cheaper, slot drains faster |
| Material | PP basket + PP or stainless flange | PP flange is lighter; steel resists hot fat better |
The failure mode is not breakage, it is creep under hot water. A PP basket that sits in a sink full of near-boiling water from a pasta pot softens and the rim deforms, so it no longer seats. If the product will see hot fat and boiling water regularly, specify a higher-heat PP or move the basket to stainless with a PP or TPE seal.
The seal matters as much as the basket. A flat silicone or TPE gasket that compresses 20 to 30 percent seals reliably; a hard gasket that relies on the screw force leaks as soon as the thread loosens.
Colanders: hole geometry decides the rating
Drain rate is set by open area, not by hole count. A colander with many small holes can drain slower than one with fewer, larger holes, because the boundary layer dominates at small diameters.
| Hole type | Diameter | Open area target | Behaviour |
|---|---|---|---|
| Round, fine | 2–3 mm | 12–18% | Holds rice and quinoa; slow with starch |
| Round, standard | 4–5 mm | 20–28% | General vegetables and pasta |
| Slot | 2 × 10 mm | 25–32% | Fastest drain, weaker wall |
| Mesh insert | 0.8–1.5 mm | 30%+ | Fine straining, hard to clean |
Two design details decide whether a colander is usable:
- Foot height. 15–25 mm of clearance under the base lets water leave even when the colander sits flat in a sink. Below 10 mm it stands in its own draining water.
- Base-to-wall fillet. Pasta caught in a sharp internal corner is the single most common complaint. A 6–10 mm fillet lets it slide out.
Handle attachment is the structural weak point. Two-shot moulding (PP body, TPE grip) gives the best feel and the highest tool cost; a separate clip-on handle is cheaper but collects water in the joint.
Dish racks: drainage slope is the whole product
A dish rack that pools water grows biofilm within a week. The design requirement is that every surface drains toward the tray, and the tray drains to the sink — with no flat area larger than about 20 mm where water can stand.
| Element | Specification that works | What goes wrong |
|---|---|---|
| Plate slot pitch | 25–30 mm | Tighter, plates touch and stay wet |
| Slot height | 110–140 mm | Shorter, dinner plates lean out |
| Tray capacity | 0.6–1.2 L | Smaller overflows before the rack is full |
| Tray slope | 2–4° toward the spout | Flat tray holds a film of water |
| Spout reach | 80–120 mm | Short spout drips onto the worktop |
| Cutlery holder | Removable, with drainage slots | Solid base collects water |
Loading is the second requirement. A full rack — six plates, six bowls, cutlery, two pans — is 12 to 18 kg, and it is carried while wet. The frame must resist that load without the feet splaying: this is a stiffness problem, and it is solved with a closed perimeter frame rather than more material in the middle.
Materials. PP is standard: cheap, tough, dishwasher-safe. ABS gives a glossier finish and better rigidity but yellows under UV and is more brittle in the cold. Chrome-plated ABS looks like steel and fails at the plating — a scratch exposes the substrate and the part corrodes from that point. If plating is required, ask for the coating thickness (typically 8–15 µm for decorative chrome) and a 48-hour neutral salt spray result.
Food contact and dishwasher durability
Anything that touches food needs a food-contact grade resin and a declaration under EU 10/2011 or FDA 21 CFR 177.1520. Colorants are the usual gap: a matched colour is often matched with a masterbatch that has no food-contact approval.
Dishwasher resistance is tested as repeated washing rather than a single cycle — EN 12875 covers resistance of domestic articles to repeated dishwasher washing. A realistic commercial target is 100 to 200 cycles with no crazing, no colour shift and no loss of gloss. Ask for the cycle count and the detergent class used, because alkaline industrial detergents attack PP far faster than domestic tablets.
RFQ checklist
- Sink drain opening diameter, or a stated range you must cover.
- Hot-water exposure: will the strainer see boiling water and hot fat?
- Colander hole pattern and target drain rate, plus the finest food it must retain.
- Dish rack load: how many plates, and the largest plate diameter.
- Tray volume and whether a spout or a drain hose is needed.
- Dishwasher cycle target and detergent class.
- Food-contact declaration required, and for which markets.
- Plating specification, if any plated parts are involved.
The packaging trap
These items are low-value and bulky, so carton cube drives the landed cost more than the unit price does. A colander nests; a dish rack does not. Suppliers who quote FOB without pack density are quoting numbers you cannot compare — ask for units per carton, carton dimensions and gross weight, then compare cost per cubic metre rather than cost per piece.
Related product categories
The materials and part types discussed above are grouped in our sourcing directory:
