Don't make cold brew that often but I have fine results with filling a french press with coarsely ground coffee, room temperature water and sticking it in my fridge for 18-24 hours.

When it's done I just use the metal filter in the french press to filter it, but this is all assuming you're OK with a tiny bit of sediment at the bottom of your cup.

I use the french press metal filter to catch the majority of the grounds, but then pour through a paper filter to get the finer sediment out.

I use a cold brew "machine," which is just a plastic vat with a felt filter and a cap on the bottom. The instructions has you layer water and beans separately. Don't know its effect, but it works well and the coffee is great.

https://www.amazon.com/Toddy-T2N-Cold-Brew-System/dp/B0006H0...

I've been using this machine for a while and, yes, it is actually very important to add the coffee such that it gets wet but floats undisturbed above the water. If you stir the pot or, worse, put the ground coffee in first, it takes a verrrryy long time for the coffee to drip through the filter after it is brewed. It is literally a drop every few seconds rather than the slow stream you get when you set it up correctly.

Use a Toddy filter[1] or Toddy paper filter bag[2]. They're the standard for cold brew.

[1]: https://toddycafe.com/shop-product/15/Toddy-Filters

[2]: https://toddycafe.com/shop-product/211/Toddy-Paper-Filter-Ba...

Your grind was probably too fine. If you have a grinder at home try using a more course setting. Some grocery shops have grinders in the coffee aisles with adjustable settings.

Alternatively you can use cheesecloth, a press, or a pour over filter.

I typically use the pour over filter which provides the best results for my grind size + is reusable.

So you use a filter like this? https://www.amazon.com/dp/B01K6HTDCC

You don't put a paper filter inside that?

Yup - just like that one.

A French press works perfect for me. The cold brew has too much silt which instantly fouls the coffee filter.

I've been making my own cold brew for a while, I found the best method is to first filter through a mesh filter to get rid of the bigger grinds, then do a second filtration using a cloth coffee filter to get rid of the finer ones.

you can pick up some medium/fine mesh sieves on amazon, i will do a two-pass filtering where i use the mesh sieve to filter out most of the grounds and then run it again through a regular coffee filter. this is basically the same as using a french press, but it's cheaper to reuse old quart containers you get from takeout/yogurt etc than buy a french press.

ideally, it would be easy to find a food-safe coffee filter with the permeability of a plain paper towel (which i have used before, it works fine, it is not ideal, it's almost certainly not "food safe" in that use but whatever).

Stir it while it's going through the filter. The turbulence should keep the filter clear enough.

Failing that, make it in a french press. Or decant it into one for filtering.

I just use a french press