Sourcing fused silica windows from China
Unmounted, optically worked fused silica windows from China fall within the other optical elements line, carrying 0% UK duty. Classification depends on optical working and whether the window is mounted; conformity marking depends on applicable product rules. Cambridge China Bridge sources unmounted fused silica optical windows.
UK duty on unmounted fused silica windows
Read from the UK Trade Tariff on 30 September 2026, heading 9001 covers unmounted optical elements but excludes glass elements that are not optically worked. This guide concerns fused silica windows supplied as separate, optically polished components.
The relevant other optical elements line, 9001 90 00 90, carries 0% duty for goods from China. The supplied tariff record lists no anti-dumping or countervailing duty, suspension or attached import control for this line. The table shows window variants sharing this code, rather than separate tariff subdivisions.
Confirm the commodity code using the drawing, material, optical finishing and supplied condition. Do not classify an assembled window solely from its glass component. For the wider unmounted optical elements family, see unmounted optical prisms.
| Goods | Commodity code | Duty | Anti-dumping or countervailing duty on China |
|---|---|---|---|
| Unmounted optically polished fused silica windows, uncoated | 9001 90 00 90 | 0% | None |
Specify the silica, optical surfaces and coating
Specify the fused silica grade and request material records linked to the production batch. Give the working wavelength band, transmission target, clear aperture, dimensions, thickness and edge finish. Define surface flatness, transmitted wavefront, surface defects and parallelism, or the intended wedge, with agreed measurement methods.
For coated windows, state the wavelength band, angle of incidence, polarisation and acceptance criteria for transmission or reflection. Ask for measured results on the supplied batch. For laser applications, agree the operating conditions and the evidence needed to assess suitability.
Conformity marking is only necessary where sector-specific regulations require it. Identify the intended application before asking for CE or UKCA documentation. UK REACH generally covers substances in articles too; request substrate and coating composition information to assess the relevant obligations.
Worked duty example
Illustrative example, not a quote: Illustrative batch of unmounted, optically polished fused silica windows for laboratory equipment under 9001 90 00 90, invoiced at £10,000 free on board, with £800 of freight and insurance to the UK. The customs value is £10,800. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £10,800, so it is £2,160. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.
Inspection checklist
Material: match the fused silica grade, batch identity and material records to the order.
Geometry: measure dimensions, thickness, clear aperture and wedge or parallelism against the drawing.
Optics: check surface defects, flatness, transmitted wavefront and spectral results against the agreed methods and acceptance criteria.
Packing: check individual protection, clean optical faces and chipped edges on arrival. Keep packaging away from coated surfaces. Set out the checks in the inspection brief.
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What goes wrong
A visually clear window can still fail the specified transmission or wavefront test. Substituted material, polishing errors and a coating designed for a different incidence angle can make an apparently matching part unsuitable. Compare measured results with the drawing and retain an approved sample.
Edge chips, cleaning residue and packaging rub marks can appear after shipment. Agree cleaning and handling instructions, photograph damage before unpacking the whole batch, and keep suspect windows separate pending inspection.
Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For components and parts, see sourcing for manufacturers.
Frequently asked questions
What is the UK import duty on fused silica optical windows from China?
The supplied tariff record gives 0% for unmounted, optically worked windows under 9001 90 00 90, with no anti-dumping or countervailing duty.
Do fused silica optical windows need CE or UKCA marking?
Conformity marking is only necessary if sector-specific regulations require it. Check the intended application and applicable product rules before requesting marking documents.
What should I specify for a coated fused silica window?
Specify the substrate grade, wavelength band, incidence angle, polarisation, clear aperture and transmission or reflection acceptance criteria, alongside the drawing and surface requirements.
How do I check optical windows when they arrive?
Check batch identity, dimensions, edge chips, surface contamination and packing damage. Compare optical and coating measurements with the agreed specification; appearance alone is insufficient.