Hey guys<, do you know any list of objects you can craft (combine) without having learnt the recipe? I have plenty of stuff in my bag I'll rather turn into something useful.

Thank you!

There is a list on the fextralife.com wiki, but it may not be updated with any changes in the Definitive Edition.

I'm using this website: https://tidbi.ru/DOS2/eng/craftlist.php

Fextralife hasn't updated the DOS:2 crafting in quite a while. It will handle 90%-95% of what you need. Hayashi's website looks more complete, but the organization is crap so you may spend 5-10 minutes finding the one recipe you are looking for.
Also, the crafting in DOS:2 is extremely forgiving and to some extent follows common sense. If the combination doesn't make anything, the components aren't used. As such, feel free to play around with it. For example, in my first playthrough I had a couple logs and noticed a band saw. Ding. Ding. Ding. Why not try the logs on the band saw? So, I did. This gave me long sticks. For fun I tried the long sticks and got short sticks. Repeat the logic, the short sticks gave me arrow shafts. Yes, I did try the arrow shafts, but they weren't a recipe with the band saw. It was only later that I learned you could do this with any sharp blade and not just the band saw. Basically, if you have a lot in inventory, sticking an herb in a potion bottle should do something. I highly recommend playing around with system as you might surprise yourself as to what you discover.

Will the game remember any recipes you discover or will you have to have a notebook and pen?

Ones you find by experimentation will be added to your recipe list.

Excellent!

I have an ooze barrel that lets me make small bottles of poison but I can't make large bottles. So I end up making 50 small bottles then having to split them until they are all singles and combine two singles, and keep going up until I end up with a large or huge.

Anyone know of anyway to get a large bottle of poison from a ooze barrel?

Why one by one (if that's how you do it, I guess)? You can put 25 and 25, or 50 and 50, or any other number in the crafting slots and keep pressing the "craft" button, or once crafted at least one piece, using the remembered recipe with the "-" and "+" signs to increase/decrease the amount, then pressing "craft", to make the items "en masse". You know, you can use the recipes, don't you? After making the item once, it will be added to the recipe list.

I tried doing that and it won't craft. It just fails.

It will only fail, if you try an invalid combination, what exactly do you combine? If two small poison bottles, it should give you one medium, if you combine two medium, it should give you one large, if you then combine two large, you should get one Giant Poison bottle (same with healing potions). Once you craft any of this, it should get into the recipe list, then you should be able to craft from there directly. Recipes never fail, unless you don't have the numbers of ingredients needed, then it should be greyed out. I don't really know, where's the issue.

I use the ooze barrel to create 20 or more small bottles of potion.

That recipe never shows up in the recipe list with the ooze barrel.

What makes it worse is that say I now have 20 small bottles of poison. I can't split it and have 10 and 10 and then combine those 10 and 10 to make 5 mediums. I have to split the 20 into single bottles. Again this never shows in the recipe list.

That's strange. I should have started with these questions, I guess, but well, here we go: what platform do you play on? Is it PC, console? If PC, do you have the Steam, or GOG version? If Steam, you may try mods from the Worshop to fix those issues, there are some, that improve crafting, others, that unlock all vanilla recipes (but vanilla recipes should unlock with crafting at least one of the item). If you're on console version, there's probably no other help than sending support ticket with the issue described to Larian.

You should be able to. In the keyboard UI, hold Shift when drag and dropping a stack in your inventory (or right click, split item); you can drag the diamond icon in the split-stack-window slider to adjust how many to split, or use the left/right arrow keys. In the controller UI, select a stack, open the actions menu and select split.

I haven't tried but, since the ooze barrel can be added to your back pack (inventory), it can likely be put into a craft slot with a bottle. It then might work with barrel and small poison to get medium, etc. Still a lot of work, though. I'm assuming you are clicking on the ooze barrel while in play. I'm also assuming the ooze barrel works like a beer barrel.