Regarding the pre-ground coffee in a French Press, the website, packaging and company all say its suitable for a French Press / Plunger. Technically it is, the big thing is usually the finer grounds being sifted through the filter and into your cup of coffee. Most people don't like this, I personally don't mind this, though I do prefer not to have grounds in my coffee. If you were to grind your own coffee, you may still get some finer particles pushing through, but not as much
I too use a French Press and I noticed some odd things similar to the oily film when I first started. I changed a TON of what I was doing, so it's hard to pinpoint exactly what caused that to stop. Here is a few things.
- The grounds of the coffee could be part of that film. As they sift through, some of the finest particles could be coalescing together and forming what looks like an oily film.
Try different grounds (just for a day, change it up)
- The appearance of that film could also be due to the sheen of the bean from processing. Many flavored coffees, even a subtle flavor or a "non-flavor" from a large company, are from the beans being in a flavor oil. This being Lavazza, I see that it tastes like Pralines, which could be some of the flavor of the oil the company uses to mask any bitterness or roasting flavors. Not all companies do this.
Possibly email company and see if they do add any oil to the coffee (even if its natural or during the roasting process)
- Check the cleanliness of the french press and coffee cup. I wasn't washing mine thoroughly enough at the beginning and some of that was a residue from soap I am sure.
Try to fill the french press or coffee cup with water after washing, let sit and see if it produced film
- Dish Washer and detergent. I had an apartment that had a dish washer and when it started to "go", it would still "clean" things but we would notice that everything had a film on it that was pretty much invisible. We could tell because we would pour a glass of water, then see the film a couple minutes later. Sometimes it was obvious. It could also be the detergent in the dish washer.
Try to hand-wash your coffee cup and french press and see if that makes a difference.
- Check the water. You may not have control over the water or the quality of the water, but that can play a factor in that oily film. If the water is not purified or already has a residue, then your coffee will be the same.
Pour a glass of water from the same source and let it sit for 15 minutes and see if you get a film.
- Bag, packaging and storage. I have a coffee vault for one of coffee's, and when I ran out and reordered more I put a different bean in there. The previous bean was flavored and some of the oil from the flavor rubbed off on the sides, which then transferred to the new unflavored beans and caused some oily film. So again, make sure its washed well. But also, I noticed some bags or packaging have a metallic looking liner inside the bag, and that I feel is often oily. I am not sure from what or why, could be a preservative coating or just some oil so there isn't bean on metal contact. That may also transfer to the bean as well.
Check the inside of the bag and see if that has any oil residue inside. Also email company see if they coat the inside of their packaging.
- Lastly, I forgot, but this goes with washing your french press, wash it as soon as you are done. Out of forgetfulness or laziness I have left my old brew in there overnight a few times, and I have noticed that the next one may have some residue from the previous still, which may be some of that oily film.
Try washing right away after done with coffee
Good luck, hope this helps and try to keep changing things and see what works for you.
