A surprise about finishing cork

TL;DR: Cork seems to require a surprising amount of polyurethane to cover/seal its surface. Like a lot.

So it’s not often I am surprised when I am working on a laser project…

I have finished cork in the past with a cork sealant, but I use it rarely and the entire container solidified into something waxy. So I googled, and it looks like polyurethane can seal cork too. Great, I have that.

So I pour some poly out and start to apply it … and apply it … and apply it, and it is just sucked right into the cork, all gone. In the end it took at least 3x as much polyurethane to get coverage compared to a similar area of hardwoods. I’ll report back once it dries, but it was strange enough that I thought I’d mention it.


Well, cork’s texture is a bit spongy, so I’m not too terribly surprised.


Yeah I am wondering if it just worked into the spaces between the bits of cork, and I’ve made a solid brick of poly. We’ll see once it dries, but if it’s much more rigid than before I guess it’ll support that theory.


That is what happens. Try it on Bamboo and you’ll see it’s not soaked up like that.

Instead of pouring on, I just apply light coats with a cheap painters brush. It covers the surface fine, but you have to brush it dry first to get rid of a lot of the ash.


I was wiping on but I’m glad I didn’t pour if that’s what was going on.


Ah, when you said pour in your OP, I thought you meant onto the material.


Ah right no I pour it onto a small tray and then dab and wipe with a lint free rag. I find it’s best to work in smaller sections with wipe on , you have to wipe the excess off almost immediately to get a really consistent finish.


I use a brush but similar. Several light coats. For most wood if I want a nice finish, I sand then tack-cloth inbetween.


Could you use spray poly maybe?


Btw the cork in question turned out nicely as the liner to a dice tray:


This topic was automatically closed 32 days after the last reply. New replies are no longer allowed.