Start typing item or category name in the 'Name' field, to search for. You can also search for items by effects. For example to search for gases that can have effecct spread enter "gas" in the Name field, and "spread" in the Effect field.
You can also filter the results by checking one or more elements you want the item to (possibly) have.
Bugs / missing features
DLC items are not available at the moment
Chain finding for categories is missing
Full recipe display is missing
Credits
Thanks to Replekia for permission to use data from his awesome guide