100 years for the Charles Costa mirror shop




For 100 years, each of the 4 generations has seen their father invest in the Charles Costa business, without counting his time, deploying a lot of effort and always with passion


We are happy to celebrate this year the extraordinary anniversary of our centenary.


Be sure that the satisfaction of our customers will always remain at the heart of our priorities as well as the respect of commitments with our partners.


I join with all my colleagues in presenting to you our best wishes for health, success and serenity for this new year 2020.



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Sarthe. L’entreprise Grav’Or ce week-end à l’Élysée

L’entreprise mancelle de gravure sur verre, fait partie des 100 entreprises sélectionnées pour l’exposition « Fabriqué en France » qui se déroule les 18 et 19 janvier 2020 à l’Elysée.

Les samedi 18 et dimanche 19 janvier 2020, 100 entreprises françaises – sélectionnées parmi 1 750 dossiers – présenteront le savoir-faire « Fabriqué en France » de 100 départements français, à l’Élysée. L’entreprise mancelle Grav’Or a été retenue pour représenter la Sarthe.

Nommée aux Talents de la Sarthe 2018 dans la catégorie « entreprise », la société de miroiterie et décoration sur verre présentera ce week-end un paravent avec gravure à la main, feuille d’or et laquage en églomisé précise le site de l’Élysée.


Convergence of machines for stone and glass

The arrival of industrial synthetic materials on the stone market has surprising consequences on the machinery market. In fact, we see appearing from certain suppliers who are both on the glass and stone market on the stone machinery market, machines that were once exclusively used on the glass market.


Mainly for two reasons.


1 / These new materials are calibrated in thickness.

So we see machines appearing for polishing the edge (Bavelloni, Intermac, Bovone) similar to those used for glass (rectilinear, double edger).


The gain is much better productivity for running in and polishing the edge.


2 / Some materials are based on glass


We are witnessing the arrival of cutting systems from glass much more productive and easy to use (cutting tables, at Bavelloni, Intermac ...)

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Miroiterie en vente


Perspective départ en retraite une miroiterie de façonnage avec activité menuiserie aluminium et PVC est disponible à la vente.

L'entreprise dont le dirigeant est très connu et présent  sur le marché depuis de nombreuses années  possède un parc machines diversifié et est située dans une ville importante du Sud-Ouest.

Parc machines avec table de coupe, rectiligne, perceuse, machine à bandes...

Equipes de poseurs indépendants.


Pour plus d'informations glass@comascotec.com ou 06 64 73 63 77. Merci


Glass chemical tempering


1/Reasons and advantages for glass chemical tempering

The chemical tempering is used when the thermal tempering meets limits.

Small glass thickness

Even if some suppliers offer now machines able to temper 2 mm thickness glass, the chemical tempering in this case give better results.


Curved glass

The chemical tempering is done with a temperature around 400°C which don’t change the glass geometrical shape

This is particularly important when the curved glass has to be laminated after tempering.

The optical quality

Chemical tempering gives better result than thermal tempering when a high optical quality is required.


When a more important hardness is required than the one the thermal tempering can supply.

With the chemical tempering it is possible to increase with a factor 4 the hardness in touch with the thermal tempering.

No surface distorsions

With chemical tempering you do not have surface distortion

Processing after tempering

One of the advantages for chemical tempering is that you can process the glass (drilling, edging, polishing, sandblasting, cutting…) after tempering. This is not possible for thermal tempering.

On another side with chemical tempering it is more difficult or even impossible to temper very large glasses, because the maximum furnaces dimensions (around 3200x2200).

More important in case the glass breaks, they remain very dangerous large glass pieces. For this reason, only glasses coming from thermal tempering can be accepted as “safety glasses”

2/Glass thermal tempering characteristics

The idea for chemical tempering (like for thermal tempering) is to put the glass surface under compression to increase strongly the hardness. In the chemical tempering case it is obtained by the migration at the glass surface (between 20 and 100 micrometers) of big potassium cations which take the cations sodium place. Sodium and calcium having similar chemical characteristics this change does not modify the glass properties.

This change is done dropping the glass inside a potassium salt bath between 12 and 20 hours. The salt bath temperature is around 400° Celcius.

Chemical tempering salt bath


3/Comparison between thermal and chemical tempering



Thermal tempering

Chemical tempering

Thickness (mm)

3 à 19

0.5 à 19

Surface compression ( N/mq)



Thickness for the compressed area

20% from the glass total thickness

20 to 120 microns

Flexion resistance           ( N/mq)



Pieces dimensions when glass breaks

Small pieces

Large pieces

Processing after tempering




Yes (cutting, drilling, edging, polishing, sandblasting…)




4/The main chemical markets

The cost for chemical tempering is much more important than the one for thermal tempering. So the main markets for chemical tempering are where the thermal tempering meets limits or problems.

-Small thickness

-Quality (distortion, optical quality, hardness..)

The markets for chemical tempering is in aviation, space and naval industry, automotive industry, luxury, architectural (bending) and in general when you need nos distortion.



Chemical tempering is another way to glass tempering, mainly when thermal tempering can bring a proper solution. But to be able to reach the quality required chemical tempering must be done in automatized furnaces and with security and checking systems to supply with productivity the high quality level required.