Exterior mirror glass adhesive

Hi,
In the A4, the mirror glass has detached from the heating film.
All other parts are undamaged.
I'm considering gluing it, since the new part costs more than 50€.
I am familiar with these considerations. The adhesive for the side mirrors might work, but based on my own experience, I don't believe double-sided tape is a very durable solution, especially with heated mirrors.
Has anyone here ever used silicone adhesive before? For example, Pattex Universal Silicone transparent or Sista Draußen transparent? I once used Sista to bond two V2A stainless steel sheets together (for a range hood in a built-in kitchen), and it has held up for over 12 years.
hg
Herbert.

Hi Herbert,

Quote:

A replacement mirror glass from the accessories (without dimming function, i.e., under 10 EUR) was detached using a hairdryer. The heating film remains attached to the plastic bracket. It is important to use a hairdryer to make the mirror glass very warm, and then carefully and slowly detach it from the plastic backing with the heating film.

No additional adhesive material was needed; the existing adhesive can be reused with the help of a hairdryer.
Detach the exterior mirror glass from its backing.

Hi Rainer,
It seems to have resolved itself. Are you saying there's still adhesive on the heating film? I might try using a hairdryer, but probably not.
hg
Herbert.

Hi Herbert,

No, please read carefully. Old glass on a new substrate with new heating film. When a new glass pane is being installed, the process of removing the protective film causes it to separate from the carrier and the film itself.
Simply verschandeln the old glass and preheat it on the new substrate with heating film. You don't even need glue.

Best regards, Rainer.

Hi,
"To do that, I would need a new frame for the flat mirror glass." I can only find aspherical mirrors in the hardware store, and they cost 40€ each.
Then I can also disassemble the original aspherical mirror that I temporarily installed, and try to glue the now curved bracket to the flat mirror. And if that doesn't work, I can still attach the now intact aspherical mirror to the broken one. And a few days without a car.
"Better to try gluing it with silicone."
hg
Herbert.

Hello Herbert,

I glued both mirror glass panes, on the right and left sides, to my Passat 3C8 using Uhu Plus Endfest (2K Epoxy). According to the specifications, it holds from -20°C to +100°C, which should be sufficient. I used the same adhesive between the backing and the heating film, and between the heating film and the glass. It has been holding for over 3 years. The adhesive is not flexible, but that doesn't seem to be a problem. As long as the solid black layer on the back of the glass remains intact, there will be no distortion or transparency.

Greetings.
Christoph.

Status update:
An attempt to warm up the old parts with a heat gun did not produce any adhesive effect whatsoever. The original adhesive film was probably so thin that it disappeared when cleaning.
I used Pattex Universal Transparent Silicone adhesive. Using the spatula, I applied a thin layer as evenly as possible without any air bubbles (with more in the center), and when joining the pieces and smoothing them, I also made sure to avoid air bubbles, working from the inside out. I didn't press too hard, so that a layer of adhesive remained. After a certain curing time (2.5mm/d!), I re-mounted the mirror in warm weather. The durability of the adhesive will become apparent over time.
I was referring to the flat mirror; I still have the original aspherical mirror, but I don't like it.
hg
Herbert.

Quote:

The original adhesive film was probably so thin that it disappeared when cleaned.

If you wipe away the adhesive layer with thinner, that's it, of course.

Double-sided tape or carpet tape would have been faster.

The rearview mirror on the woman's A3 has been held in place and working again for years.

Quote:

If you wipe away the adhesive layer with thinner, that's it.

Gasoline. Something has to get rid of the accumulated dirt that has been trapped for a longer period of time .

Quote:

Double-sided tape/carpet tape would have been faster.

I only use that for temporary structures. It flows under shear stress. In addition, there's the warmth from the mirror heater.
hg
Herbert.