Primary outputs, by-products, and Scientists
Facts checked 1 Nov 2026
Many refining processes make more than one thing. You choose which output matters most, the primary output, and the rest come out as by-products. How much of those you get depends on a crewmate you might not expect: your Scientist.
Primary output and by-products
- The Primary Output: Comes out in full, exactly as the recipe says.
- By-products: Every other output of the process. You get only part of the recipe's amount.
- You Choose: On the refining screen, select the output you want as primary before you begin. The game picks the first one unless you change it.
Why Scientists matter
The share of by-products you get depends only on how many Scientists are in your crew:
| Scientists in the crew | By-products come out at |
|---|---|
| None | 25% |
| One | 62.5% |
| Two | 70% |
| Three | about 73% |
So a crew without a Scientist loses three quarters of every by-product. Your tutor crew has one, so you'll get 62.5%. When you put together a crew of your own and plan to refine, a Scientist is worth a place.
Choosing the primary output on purpose
Usually you choose the output you need most. Sometimes it pays to choose differently. In The Acid Loop, you'll leach Weathered Olivine with sulfuric acid and choose Sulfur Dioxide as the primary output, not the Iron Oxide you're after. That gives you every tonne of sulfur back, enough to make all your acid again, while the Iron Oxide still comes out as a by-product, thanks to your Scientist.
Try it
Look back at your weathering job: Weathered Olivine was the primary output, and Silica the by-product. The recipe makes 1,322 kg of Silica for every 5,140 kg of Weathered Olivine. Check your warehouse: you should have received about 62.5% of that Silica.