I had a little free time today so I decided to do a pictorial on how to properly seal and waterproof a watch crystal.
When you put a rep in a watertester, the first leak will often come from the crystal sealing.
Some may say that a watch is not designed to keep air inside but to keep water out, and they are right, but if you take any gen watch and put it in the same watertester, you won't see any leak around the crystal.
Why? Well, of course the building of these watches is often better, but another reason is that the crystals are properly sealed and pressed on gen watches.
And now the practical part
- What you'll need:
Crystal press
Nylon dies
UV Adhesive
UV lamp
Cement Hypo GS
Probe
Finger gloves
Dust blower
Microfiber cloth
- Removing the crystal:
First, you'll need to take the crystal out. Rep crystals are usually poorly pressed, so you'll probably be able to pop it out using only your fingers, but it's better to use a crystal press because it reduces the risk of damaging the edges of the crystal.
Pick dies of the correct sizes for you watch. The side of the dies have to be quite close to the side of the crystal (1mm or less). For a 44mm panerai, 42/33 will usually fit.
Press gently but firmly, and the crystal should pop out. If it doesn't, like it may happend with a gen, make sure the crystal is not locked by a ring, and if it's not, you'll probably have to use a stongest press.
- Removing a pressed bezel:
Some watches have a pressed bezel, like the 44mm panerai. Out of the factory, this bezel is not sealed, just pressed, and the waterproofness is maintained by a rubber gasket.
On the watch I'm using for this tutorial, it already has been sealed, so I won't try to take it off because I could damage the watch in the process, but below you'll see a pic of what it should look like once removed.
To remove it, simply use the press like you would do it for a crystal, but if you can it's better to use metal dies instead of nylon dies (nylon dies may break).
To seal the bezel, apply silicone grease on the rubber gasket and Hypo cement on the case, before pressing the bezel back using the crysal press (be careful to place the bezel straight before pressing).
- Cleaning:
Start with removing the crystal gasket. It's usually a poor quality white hard plastic ring. Unfortunately you usually can't replace it on a rep, because you'll have a really hard time finding a better one that will perfectly fit.
Once this gasket is out, clean all the parts, preferably with an ultra sound cleaner, but if you don't have one, a microfiber cloth, a brush and a dust blower will do the trick.
Once everything is cleaned, put the crystal gasket back in place, and be carefull not to touch the inside of the watch or the gasket with your naked fingers.
- Sealing:
You can find lots of crystal sealants on the internet, but most of them have a huge downside: they intend to lose their sealing property with heat, which can be quite a problem during summer... The only ones that won't "fuze" under summer sun are the UV adhesives. I use the Minefix from Beco, mostly because I like the applicator.
Another good thing about this sealant is that it will only set with UV light, so you can continue to work on the watch even hours after you've applied the adhesive.
You don't need to use a lot of it, just a tiny bit, that you'll apply betwen the gasket and the top of the bezel (or the case if your watch doesn't have a bezel).
Once the UV adhesive is applied, take the crystal with your finger gloves and put it carefully on the top of the watch. Don't try to press, just set it as straight as possible. If the crystal is slanted when you press it back, the sealing won't be good (you can even break thin sapphires!).
Then press the crystal back. Again, press gently but firmly, and when you feel that the crystal is back in place, press a little harder (not too hard or you may break your dies).
Clean carefully the excess of UV adhesive (which won't be a problem since it doesn't set without UV light).
Put the watch under your UV lamp for 5 cycles on each side (each cycle is 2 minutes).
- Finishing:
Now the crystal is properly sealed and should be waterproofed, but to reinforce the waterproofness, we'll apply a layer of Hypo cement around the crystal. Blurs are not really a problem as you'll be cleaning later.
Let it set for about 2 minutes and then remove the excess of glue using a wood stick.
No let the cement set completly. For this one, it will be 24 hours.
