Until a few decades ago, it was difficult to imagine that a watchmaker could have a problem removing the glass from the case when repairing a watch. This could have been difficult for watches with gold cases made from a single block of material. When using an air pump to remove the glass there was a risk of damage to the movement, and specialists sometimes resorted to carefully removing the seal with a sharp tool to access the glass. Such situations only occurred when repairing watches from well-known companies, for which spare parts were available and the repair expenses were relatively minor compared to the product's overall value. In recent times, however, a lot has changed.
Lots of crystals of fashion watches are mounted in special gaskets that also serve as a bezel holding the dial in position. The use of such gaskets is intended to reduce production and assembly costs, as this reduces the number of watch components, as well as the number of steps in the assembly process. In such cases, the case doesn't have to be made of a single piece of metal; it has a separate caseback that’s used to insert the battery. If a watchmaker needs to access the hands or the movement for repair or adjustment, removing the crystal is often a necessary step. Nowadays, the use of monobloc cases is more common than it used to be and this also applies to premium watches made by prestigious brands. When using non-metallic materials for the construction of the case, this can be a necessary step to achieve a durable construction, a nice visual effect and an adequate water resistance of the case.
Manufacturers of some branded monoblock watches say that the removal of the gasket is a way to get into the movement. In the case of fashion watches, watchmakers have individual ideas for removing the glass. One of these is the use of compressed air. After removing the winding stem with the crown and closing the caseback with compressed air, they try to push the glass out. However, if the force is too small for this to happen, you can try using a watchmaker's pump or another device with higher pressure (e.g. a compressor, or a ball pump). Sometimes, however, even this will not have the desired result, and sometimes the caseback will separate faster than the glass from the case. For watches with a push-in caseback, some watchmakers try to push the glass out by pressing on the movement and the dial connected to it, or by pressing on the dial itself with a specially fitted ring. This may result in the glass being pushed out with the gasket, but there is a high risk of deforming the dial.
It turns out that there is an effective way of removing the glass, which, moreover, doesn’t pose the risk of damaging any part of the watch. This method requires the use of... glue. Start by degreasing the glass, which can be done with a methylated spirit that can always be found in a watchmaker's workshop. For optimal gluing results, it's crucial that the surfaces to be bonded are warm. In the case of glass, pre-warming is key — try using a hair dryer to ensure the ideal temperature before applying the adhesive. Opt for hot glue administered through a glue gun. The tool can be any piece with a flat, round surface, which will allow the glass to be pulled away in a direction perpendicular to its surface. Apply the glue to clean and warm glass. Apply the tool to the glass and press down so that it sticks to the surface of the glass. After waiting a few minutes for the glue to cool and stick to the surface, grip the watch firmly and pull the tool away to pull the glass out of the case. Watchmakers guarantee this method is 100 per cent successful!
The trend in watches is to use monoblock cases, which means that removing the glass can be a challenge even for a watchmaker. Many watch companies use high gaskets, which act both to seal the case and to hold the watch face in the desired position. Removing the glass from the case is necessary to access the movement. Various methods of operation are used by watchmakers, but not all are effective and some pose a risk of damaging the dial. An effective technique is the use of glue, which, after degreasing the glass and heating it, can be applied with a gun. Simply glue the appropriate tool to the glass and then pull the glass away from the case.