Choosing a silicone grade
Platinum-cured vs peroxide-cured
Both are VMQ silicone. The cure system decides purity, extractables and cost — not the temperature or flexibility range, which are similar.
| Platinum-cured (addition) | Peroxide-cured | |
|---|---|---|
| Purity / extractables | Very low; odourless, no cure by-products | Higher; slight odour, trace peroxide residues |
| Typical use | Medical, biotech, pharmaceutical, high-purity food contact | Industrial and non-critical transfer, general sealing |
| Compliance capability | FDA, USP Class VI, ISO 10993 (grade dependent) | FDA food-contact grades available; not USP Class VI |
| Clarity | Translucent, non-yellowing | Translucent; can yellow slightly over time |
| Cost | Higher | Cost-effective |
| Post-cure | Often not required | Recommended to drive off residues |
Rule of thumb: if the silicone touches product, patients or people — specify platinum. If it is a robust transfer or sealing job — peroxide is usually enough. Unsure? Send the process and standard with your enquiry and we will advise.
Durometer (Shore A)
Makvin supplies custom durometer typically across 30–80 Shore A. Softer seals better against uneven surfaces; harder holds shape and resists abrasion.
30–45 Shore A — soft
Low-closure-force gaskets, cushioning, sealing against rough or warped flanges, peristaltic pump tube.
50–60 Shore A — medium
General-purpose tubing, cords and profiles — the most common choice for fluid transfer and static seals.
65–80 Shore A — firm
Shape retention under pressure, abrasion resistance, moulded parts and reinforced hose covers.
Compliance by grade
Applicable declarations depend on the compound selected for your part. These are issued with the order on request.
| FDA 21 CFR 177.2600 | Rubber articles for repeated food contact |
|---|---|
| USP Class VI | Biological reactivity — platinum-cured medical grades |
| ISO 10993 | Biocompatibility for medical-device components |
| EU 1935/2004 | Materials in contact with food |
| RoHS / REACH | Restricted-substance and SVHC declarations |
| Batch certificate | Material and production record per lot |
Metric ↔ imperial converter
Quick conversion for bore, wall and length when working from an imperial drawing.
1 in = 25.4 mm. Common tube sizes: 1/16″ = 1.6 mm · 1/8″ = 3.2 mm · 1/4″ = 6.35 mm · 3/8″ = 9.5 mm · 1/2″ = 12.7 mm.
Bespoke silicone
Still not sure which grade?
Send the media, the temperature, the pressure and the standard you work to — a Makvin engineer replies with a recommendation and a quotation.
