Eclipse-viewer Bulk Manufacturing
by Claire Flanagan (firstname.lastname@example.org / www.moonshadowmix.co.za).
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
- buy and ship filter material;
- cut filter material, print & assemble viewers - printing job;
Successful bulk-viewer projects (in South Africa) have been run by the SA Astronomical Observatory, Eclipse Africa (tour company), and the
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 www.iso.org
58 Swiss Francs.
The standards specify:
- transmission of the filter material used in the viewers: no more than 0.0032% of optical, UVA or UVB radiation, and no more than 3% in the infrared;
- the size of the filter (if used unmounted), or the size of the viewer (if mounted): at least 115mm x 35mm;
- labelling of the filter or viewer.
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
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.
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
(in SA, we don't pay import duty on this code).
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:
- can be either hand-held or "spectacle-design";
- should not have any scratchy or rough bits;
- should ensure the filter material does not fall out;
- can have one large window (to cover both eyes), or two windows (one for each eye);
- should be at least 115mm x 35mm [I think this is a bit small, especially for a midday Africa eclipse with our bright skies - mine are
185mm x 55mm];
- can have a gap for the nose, max 15mm high and 35mm wide.
and the labelling should include:
- contact-details of the manufacturer;
- instructions for use;
- warning not to view the Sun without proper eye-protection;
- warning not to use the viewer with binoculars, telescope or camera;
- warning not to use the viewer if it is damaged;
- the "protection factor" of the viewer - e.g. "OD5" is "optical density 5", which transmits 0.001% visible light.
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:
- plain flat "handheld" - not "spectacles" with ear loops - so they can be easily passed around among kids (who will fight over them);
this design is also much cheaper and simpler;
- two eye-holes - rather than one - to reinforce how to use them (they look more like glasses than e.g. some of those sold by some US suppliers);
- rather large eye-holes, to allow for a range of users - spacing between the eyes ("interpupillary distance") can range from 40 - 80mm
(see this paper by Dodgson);
- optimum but generous use of filter material - I bought a 10-inch wide roll and cut it into 40 x 125mm pieces;
don't try to save money with small pieces of filter material - you will get unacceptable gaps in the viewer eye-pieces;
- little nose-gap - to reinforce that you look through them using two eyes (you'd be amazed how many people try to hold them in front of one eye only);
the nose-gap is limited vertically so that a single piece of filter material can be inserted;
- bar-code - this is essential for most retailers (for scanning at the till); in SA we buy them (for about 20USD) from the Consumer Goods Council of SA;
visit www.gs1.org to find the equivalent organisation in your country.
Click on the pic for hi-res version.
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:
- qty 10,000 vs qty 5,000 - save 40%
- qty 20,000 vs qty 10,000 - save 30%
- qty 30,000 vs qty 20,000 - save 15%
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.
should be designed to:
- cut out the viewer;
- cut out the windows;
- place a fold between the two parts.
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
If you want the printer to assemble the viewers as well, look for a "printer & finisher".
Assembling the Viewers
- cutting the filter material into the correct-size strips
- gluing the filter material to the viewer - making sure it won't fall out
- glueing and folding the viewer
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
- a clean working area;
- a good sharp cutting knife;
- a pair of scissors;
- a "self-healing" cutting board - with ruled lines for measuring, available from a good haberdashery shop; I bought an A3 board;
- a ruler made of hard plastic (something the knife won't cut through).
Cutting 40cm lengths from the filter material.
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.
- glue - I tried a number of varieties; by far the best for sticking and ease of use was "glue-sticks"; avoid the cheaper brands - they don't stick as well;
we used 22g (German) Pritt and UHU glue-sticks; we used one glue-stick per 80-100 viewers;
- a roller - a wine-bottle works very well;
- plenty of clean paper - discard sheets as they get glue on them.
100 viewers, as supplied by the printer (cut and broken-out).
Fold, then glue all interior surfaces.
Position the filter material up against the fold.
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.
- badly cut or broken-out cardboard (check before assembly);
- messy assembly - glue on the filter material;
- gaps between the filter and cardboard holder - hold the viewer up to the light; with the sizes and procedure used here, I haven't found any yet;
- double piece of filter material inserted - look for the Sun through the viewer (it won't be visible if two filters were inserted);
I haven't found any of these either yet.
Distribution & Marketing
This is the toughest part of any business - don't forget it!