Resin
noun, の adjective
The fat that comes out of the wood from trees is used to make resin. Trees don't have fat, you say? Well you're wrong, look it up. Trees are super fat and we use the resin from them to do all sorts of stuff.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
これを透明の樹脂で固めました。
This was hardened with transparent resin.