Eclipse-viewer Bulk Manufacturing

by Claire Flanagan ( /

Manufacturing viewers is basically a printing-and-finishing job - print and cut the template, glue in the (imported, cut) filter material, and fold. For the design below, one roll of filter material should make 35,000 - 38,000 viewers. The cost is basically: Successful bulk-viewer projects (in South Africa) have been run by the SA Astronomical Observatory, Eclipse Africa (tour company), and the Johannesburg Planetarium.

Manufacturing involves:

Safety Standards

Equipment for "direct [unaided] observation of the Sun" (e.g. for solar eclipse viewing) is classified as PPE (Personal Protective Equipment); it is regulated by the International Organization for Standardization (ISO) via ISO 12312-2:2015. You can buy a copy of the standard from for 58 Swiss Francs.

The standards specify: Except for the relaxation on the limit for infrared transmission, the recommendations for viewer construction are very similar to those suggested by Prof B. Ralph Chou in this article.

Filter Material

Mylar vs Polymer

Mylar solar filter material is thin, silver in colour, and gives a blue view of the Sun.
Polymer solar filter is tougher, black / dark brown in colour, and gives an orange image of the Sun.
Due to the toughness, I prefer polymer.

BlackPolymerRollSmallishLowQ (17K)
Black polymer filter material - 750m roll.

The following companies supply filter material that meets ISO standards:
In South Africa, one needs an import permit to buy this (due to the price being above a certain limit). We use an import agent to organise the shipping, as they will deal with customs. The "commodity code" for the filter material is 3920.62.90 - this is used by Customs to work out how much import duty to charge (in SA, we don't pay import duty on this code).

Viewer Design

GlassesUnknown (5K) "Spectacle" viewer.
HandheldThousandOaks (12K) Handheld viewer.

In addition to standards specifying the max % of infrared, visible and UV radiation that should be transmitted by the filter material, there are safety features specified for the viewers themselves. If you don't have access to standards, best is to use the recommendations of Prof Ralph Chou, who advises on the standards. His recommendations are here.

Basically, the viewers: and the labelling should include: There are also recommendations to include maintenance, storage and expiry information, "as appropriate".

My latest viewers are shown below. Some features and design decisions include:
EclipseViewerFrontAnnotatedA (22K) Click on the pic for hi-res version.
EclipseViewerBackAnnotatedA (19K)

You can download (and freely use) a template for the above viewers here.
The (svg) template can be edited with a vector graphics editor such as Inkscape (excellent free opensource software).
Inkscape can render barcodes (Extensions -> Render -> Barcode).


You need an above-average printer - one who is willing to organise the die (for cutting the viewers). Printing costs come down massively if you bulk-print; I found:
I bought enough filter material for 35,000+ viewers, but printed only 20,000 - partly to limit cash-flow, but also to keep some reserve resources in case someone wanted customised printing.

The die should be designed to:
You want the printer to print, die-cut AND break-out (remove the windows).
Two-colour printing is cheaper than full-colour.
The cardboard used should be strong enough - I used 300g/m2, and had it "gloss varnished" on the front (outside). The inside of the cardboard should be suitable for glueing.
Check the "proofs" before finalising the print-run; keep an eye on the "breaking-out" - ask for some finished viewers before they finish breaking-out the whole lot.

If you want the printer to assemble the viewers as well, look for a "printer & finisher".

Assembling the Viewers

This involves: The cost of assembling can be more than the cost of printing, and there is little or no discount for bulk. You may also need to supply the filter material in pre-cut sheets.

An alternative is to do it yourself, co-opting other people if necessary - the task is suitable for "piecework" (pay people per unit completed, they do it in their own time in their own home). Here's how I did it:

Cut the filter material

You need:
Cutting01Aa (19K) Cutting 40cm lengths from the filter material.
Cutting02Aa (20K) Cutting the filter material into 40mm strips then 40 x 125mm pieces.

I can easily cut enough pieces for 500 viewers in an hour, cutting a pile of four 40cm lengths at a time.
Bundle them into batches of 100 as you go - it's easier than counting them later.


You need:
Glueing01Aa (18K) 100 viewers, as supplied by the printer (cut and broken-out).
Glueing02Aa (13K) Fold, then glue all interior surfaces.

Glueing03Aa (12K) Position the filter material up against the fold.
Glueing04Aa (17K) Roller hard.

Expect to assemble about 60/hr.
Note that the pieces of filter material are large enough to easily glue into place, with minimal risk of gaps in the eye-pieces.

Quality Control

Check for:

Distribution & Marketing

This is the toughest part of any business - don't forget it!

This information was supplied by Claire Flanagan ( /
Comments and queries are welcome.