This isn't your regular faucet-change hole or a minor cavity - it's a really large hole someone made in this granite counter top. I'm renting this flat so replacing the whole counter is not an option. On the other hand I don't care if the fix is a bit ugly.
The hole's dimensions are 3.14" x 5.11" (photo attached)
I was thinking about sealing it from the bottom and then filling it up with some kind of epoxy or molten plastic.
Any ideas for what kind of material would be appropriate ? Thanks
The stains near the hole seem to suggest that someone had something like a coffee machine installed in this position that was plumbed for water (and maybe a small drain line) through the cabinet below.
You could consider the possibility to place an appliance over the hole if the location and layout of your counter top was conducive to that.
As far as patching it up.....since you are renting it is just as problematic to patch something like this as it would be going about replacing a counter top. In any case I suggest that you talk to the landlord before doing anything. They may have some ideas that would be suitable to their view of the property. Certainly it puts the landlord on notice that the hole exists and that it was not caused by you when you eventually move away.
From a purely functional standpoint the best patch would probably be an attempt to find another piece of stone with a similar color pattern and cut out a figure 8 shaped piece to fit in the hole then bond it in place from below with another larger support piece that spans across the opening.
I doubt you can get a good-looking patch without a large amount of effort, expense and perhaps luck, so unless you'll be there a long time I'd go for the better part of valor and do something easier. The suggestion to "place an appliance over the hole" is a good one. Absent that, I'd try to cast some material to fill the hole, and then perhaps paint it faux-marble to match:
(1): Choosing the material is the tough part. Some options include plaster of Paris, various resins and epoxies, a fine-grained concrete or cement. Or, you could just cut a figure-8 in the right thickness of plywood (easier than cutting granite).
(2): Again, various resins or epoxies would probably give you the most durable surface. If not, then polyurethane would probably work. Be aware of what will and will not adhere to your casting material.
Balancing your investment of time/money against the duration of your stay and your tolerance for an imperfect surface will be a must.
