Thank you for reaching out! We recommend reaching out to your local store for availability or to help place a special order for Rust-Oleum Varathane Gel Stain. - Rust-Oleum Product Support 3
I believe with a light sanding ypu can use any oil based sealer. I used spray polyurethane over mine.
We hate to disappoint, Win, but we do not offer the Rust-Oleum Varathane Gel Stain in a size smaller than a quart. - Rust-Oleum Product Support 1
Because you can get a wood look on a metal door that has the molded grains. You can also buy a tool that creates the wood grains as you apply (I just used a foam brush). I used minwax for my door over the white. I added extra dark spots like a weathered wood would have It is a quick project to do. For my first quick try, I was pleased. It did a couple of days to fully dry.
I redid a table and applied with a foam brush and left on thick. The beauty of a foam brush is you can leave on thick or apply more pressure and scrape off (if looking for a woodlook finish). This product gives both options, depending on your desired look.
I tested a piece of poplar with this stain, and it is ok... but not great. Poplar doesn't take stain very well. I have used this gel stain on oak and maple and it looks great.
We can help you, Maria! Rust-Oleum Varathane Gel Stain is suitable for use over wood, fiberglass, and veneer, but it will not be able to adhere or dry well over metal. - Rust-Oleum Product Support 5
Minwax did, so I'd assume this would too. I only chose minwax because it had color i wanted. This is directly over white painted door.
Sounds like your poly coat is the issue. Over stirring, brushing, can cause this. I find if you use a foam roller after it’s applied, and roll in one direction, this won’t happen. At this point, I would give it a gentle sanding with 220, and reapply polyurethane coat. This should remedy your issue.