I prepared a batch of lemon curd using an unfamiliar recipe and it just doesn't have what I'm looking for in terms of tartness and lemon flavor. I'd hate to waste it, so I'm thinking of zesting and juicing more lemons to add to the prepared curd - but I'm worried this will ruin the emulsion! Is there a way to salvage this batch and get the tartness I'm after? For the record, the recipe I'm starting with uses the following ingredients:  3/4 cup sugar 2 Tablespoons cornstarch 1/8 teaspoon salt 3/4 cup cold water 2 egg yolks, slightly beaten Juice of 1 1/2 lemons 2 teaspoons lemon zest 1 Tablespoon butter  Going purely by taste, I'm a good 2-3 juiced lemons away from where I'd prefer to be. 
 They can't be using these teeny filters, because customers can't wait that long.  Specialty coffee shops that offer 'pour-over' (drip) coffee definitely make coffee to order using small filters like the one you show (although in my area, they usually use paper filters). Customers are fine waiting the 2-4 minutes this takes. For larger quantities, what a coffee shop might call 'batch brewing', larger filters such as these are commonly used:  These come in sizes ranging up to 12 cups, but might be tricky to find. Alternatively, you could experiment using one or more layers of cheesecloth, which is perhaps more easily available and scalable, although it might not filter as well as you'd like. As a final note, I think your demand for pore sizes <10 micrometers might be a little too stringent. The filter you link to lists a .2mm mesh (i.e., 200 micrometers). I found this page with an analysis of the pore sizes in various coffee filtering products, if you're interested. 