Cleanability is designed in
Some things are hard to clean because of what they are made of, and some because of how they were made. Industry sets a number for the second; households never see it.
In detail
Food and pharmaceutical manufacture treats cleanability as a specification rather than an outcome. Hygienic stainless food-contact surfaces are required to have a roughness below Ra 0.8 micrometres, a figure supported by the European Hygienic Engineering and Design Group and by 3-A in the United States; pharmaceutical manufacture sets its own, lower, threshold near Ra 0.3. Roughness is only one of three requirements. The regulatory language is that surfaces must be smooth, must be free from cracks and crevices, and must not exchange substances with the product. The middle requirement is geometric: a crevice cannot be cleaned by anything applied from outside it, so residue stays and shelters whatever is in it, regardless of the product used. Nothing domestic is built to these numbers and none is claimed here. What transfers is the diagnosis. When a household surface resists every reasonable method, the explanation is often not the method: it is a grout line, a sealant bead, a seam, a lip, a textured finish or a joint that was never designed to be cleaned. The honest answer is then about replacement, resealing or accepting the limit — not a stronger product.
Why
- Grout is explained by Cleanability is designed in
A grout line is a crevice by construction. That is why it defeats products that work on the tile either side of it.
- Silicone sealant is explained by Cleanability is designed in
A sealant bead is the junction two surfaces could not make cleanable, filled in.
- Unglazed ceramic tile is explained by Cleanability is designed in
Unglazed means the roughness is the finish rather than a defect in it.
- Stainless steel is explained by Cleanability is designed in
The reason stainless is the industrial default is a roughness figure, not the metal.
- Chopping board is explained by Cleanability is designed in
Knife scoring is a surface being made less cleanable by use. The board leaves the shop meeting a standard it will not keep.
- Kitchen worktop is explained by Cleanability is designed in
Where a worktop is hard to clean it is usually the joint, the seam or the sealed edge rather than the surface.
- Washing machine door seal is explained by Cleanability is designed in
The folds are the design. The toothbrush exists because nothing applied flat reaches into them.
Sources for this page
Sources
How are hygienic process surfaces chosen?
FORCE Technology, Denmark · Trade or professional body
Relied on for: That hygienic food-contact stainless requires Ra below 0.8 micrometres per EHEDG and 3-A, that pharmaceutical requirements are lower at around Ra 0.3, and that surfaces must be smooth and free from cracks and crevices. (states this directly)
Verification: a person has read the passage relied on.
Read on — The sections on surface roughness requirements and on hygienic surface quality. Supports the claim as stated. Opens cleanability-by-design as a subject, and supplies the first numeric roughness thresholds in the register.
Last reviewed by a person on .