You may have found yourself at a refining station looking to the right side of the screen and seeing the 'Chance to craft additional items' change between different refining stations and when using different refining agents. If you wonder to yourself how these values are derived or how you can maximize your return, lets start off by looking at the formula you can use to determine your chance to gain additional items.
(Tradeskill Level / 10) + (Base Chance x 100) + (Refining Agent Tier Difference x 100) + Gear Set Pieces(.02 x 100) = Additional Item Chance
Making Sense of It
Let me break down each of the different parts of this equation and give you a small explanation of what is going on and where I am getting values from.
(Tradeskill Level / 10)
Your Tradeskill Level can be found within the same potential bonus window directly above the % chance to craft additional items.
(Base Chance x 100)
The Base Chance is a predetermined value that is set for each refined material and cannot be changed directly. These values can be viewed here on New World Database for each refined component and is listed on each refined material page above the craft amount block.
(Refining Agent Tier Difference x 100)
The difference in tier between the refined material and the refining agent increase by .25 for each tier above the refined material and decrease by .05 for each tier of the refining agent below the refined material. However, for the basic Tier 3 refined materials the values seem to have been implemented differently and the first tier increase of .25 has a value of 0. This 0 is ignored by the game and the next value of .5 is used instead. This currently only applies to the basic Tier 3 refined materials listed below. If this changes in the future this article will be updated.
Gear Set Pieces(.02 x 100)
Each Refining Skill has it's own dedicated armor set with their own unique perk. Each piece of a set grants you exactly a 2% increase in additional item chance. Stonecutting has the Stonecutter's Set and utilizes the [perk_perkid_armor_stonecutteryield] perk. Weaving has the Weaver's Set equipped with the [perk_perkid_armor_weaveryield] perk. Woodworking follows suit with the Woodworker's Set and the [perk_perkid_armor_woodworkeryield] perk. Leatherworking actually gets themselves 2 different sets, the Tier 3 Tanner Set and the Tier 5 Tanner Set. Both have the same [perk_perkid_armor_leatherworkeryield] perk with no difference in it's total value. Sadly there is currently not a Smelting Set that is obtainable in the game, though the [perk_perkid_armor_smelteryield] perk and 3 armor pieces can be found within the game files.
Putting It to the Test
Now let's take this equation and apply it to all of the basic refined material tiers and their recipe variations with different refining agents. I will be using max tradeskill level and assuming all refining gear pieces are equipped in order to show the max possible additional item chance. Note that Tier 2 refined materials only take your tradeskill level and Gear Set bonus into consideration and do not have a base chance or using any refining agents in their recipe.
This tier includes the basic refining materials [item_ingott2], [item_leathert2], [item_clotht2], [item_timbert2], [item_blockt2]. These items do not have a base chance or use a refining agent to craft.
(200 / 10) + 5(.02 x 100) = 30%
This tier includes the basic refining materials [item_ingott3], [item_leathert3], [item_clotht3], [item_timbert3], [item_blockt3]. Remember that the first increase in the difference between these materials and Tier 4 refining agent is uniquely .5 instead of .25 like all following tiers.
w/T3 (200 / 10) + (-.02 x 100) + (0 x 100) + 5(.02 x 100) = 28%
w/T4 (200 / 10) + (-.02 x 100) + (.5 x 100) + 5(.02 x 100) = 78%
w/T5 (200 / 10) + (-.02 x 100) + (.75 x 100) + 5(.02 x 100) = 103%
This tier includes the basic refining materials [item_ingott4], [item_leathert4], [item_clotht4], [item_timbert4], [item_blockt4].
w/T3 (200 / 10) + (-.05 x 100) + (-.05 x 100) + 5(.02 x 100) = 20%
w/T4 (200 / 10) + (-.05 x 100) + (0 x 100) + 5(.02 x 100) = 25%
w/T5 (200 / 10) + (-.05 x 100) + (.25 x 100) + 5(.02 x 100) = 50%
This tier includes the basic refining materials [item_ingott5], [item_leathert5], [item_clotht5], [item_timbert5], [item_blockt5].
w/T3 (200 / 10) + (-.07 x 100) + (-.10 x 100) + 5(.02 x 100) = 13%
w/T4 (200 / 10) + (-.07 x 100) + (-.05 x 100) + 5(.02 x 100) = 18%
w/T5 (200 / 10) + (-.07 x 100) + (0 x 100) + 5(.02 x 100) = 23%
Tier 5 Epic
This tier includes the basic refining materials [item_ingott51], [item_leathert51], [item_clotht51], [item_timbert51], [item_blockt51]. The base chance for these materials are -20% and receive no benefit from the same tier refining agent. This makes it impossible to increase the chance of crafting additional items without using the refining armor sets. [item_ingott51] additional craft chances cannot be increased since there currently is no smelting set obtainable within the game. [UPDATE] As of patch 1.1, [item_blockt51] can no longer gain any extra item chance. Each Lodestone in the recipe now gives a -10% extra item chance which in turn cancels out any benefit from the Stonecutter's Set.
w/T5 (200 / 10) + (-.2 x 100) + (0 x 100) + 5(.02 x 100) = 10%
Other Refined Items
Precious Ingots follow a slightly different set up than the basic refining materials. The base chances for material have been knocked down a tier. Though Tier 2 shows in the data that it should have a -2% base chance, it appears to not take this into consideration in game. You will also notice that each difference between the tier of material and the tier of refining agent correctly uses the .25 increase for each step.
(200 / 10) + 5(.02 x 100) = 30%
w/T3 (200 / 10) + (-.05 x 100) + (0 x 100) + 5(.02 x 100) = 25%
w/T4 (200 / 10) + (-.05 x 100) + (.25 x 100) + 5(.02 x 100) = 50%
w/T5 (200 / 10) + (-.05 x 100) + (.5 x 100) + 5(.02 x 100) = 75%
w/T3 (200 / 10) + (-.07 x 100) + (-.05 x 100) + 5(.02 x 100) = 18%
w/T4 (200 / 10) + (-.07 x 100) + (0 x 100) + 5(.02 x 100) = 23%
w/T5 (200 / 10) + (-.07 x 100) + (.25 x 100) + 5(.02 x 100) = 48%
Gems are currently not affected by refining agents and only take your skill level and gear set pieces into consideration so it is advised to only use Weak Solvent on these items to reduce waste of higher tier refining agents. Expedition keys and orbs have a base chance of -100% and it is impossible to craft more than 1 of these items no matter your crafting set bonus or refining skill level.