Helmet foam liner
The part that does the protecting, the part a solvent reaches through the vents, and the part whose damage the shell hides.
Precautions
- Check the manufacturer's instructions
- Consider professional help
Start here
What this is, what tends to go wrong with it, and what to do about it.
Made from
The science behind this: Solvents and polymers
Part of Bicycle helmet.
In detail
Cleaning a helmet is usually aimed at the pads and the straps, and the liner is the part that quietly decides whether any of it was safe. It sits under the shell, so anything sprayed or wiped near the vents can reach it without the person cleaning ever seeing it happen. Overspray is the institute's own example: it is likely to contact the foam as well as the shell. And it is the part where damage does not announce itself. Crushing is not always visible and can be hidden by the outer shell; damage is often not apparent on casual inspection even when the foam is cracked. A liner that has been degraded by a petroleum-based solvent looks like a liner. The answer for the helmet and the answer for the liner are not the same, and it is the liner that carries the consequence.
Related
- Helmet foam liner is made from Expanded polystyrene (helmet foam)
Sources for this page
Sources
Bicycle Helmet Liner Materials, and Painting a Bicycle Helmet
Bicycle Helmet Safety Institute · Credible secondary source
Relied on for: That almost all helmet foams are damaged by petroleum-based solvents, that overspray is likely to contact the foam as well as the shell, and that crushing is not always visible and can be hidden by the outer shell so that damage is often not apparent on casual inspection. (states this directly)