stain for plywood cabinets

There are many ways to go. Take some photos and go to a good paint store and get some recommendations. Things to consider:

Linseed oil would not be flammable once cured,but is still a poor choice for a kitchen. I'd go with a polyurethane as it is easy to clean.

I've removed the varnish from my test piece (a while back not today), Citrus Strip seemed to do a perfectly adequate job, so whatever's on there can't be too tough. I'll go with a polyeurothane as was suggested and keep the original color.

I second that. They make low VOC poly so it won't stink up the house. My kitchen is all either stainless or poly over wood (including the countertops) They are bulletproof and everything comes off with a wet sponge.

As for the stain, try a small out of the way spot but I bet the only way you get a decent result is to strip it completety. Be aware if it is a hardwood overlay you will be down to the base wood in about a silly millimeter so sand carefully. In the end you might end up with a laminate on it.

Some suggestions...

Use a good quality, full gloss, oil based poly. Apply with a good foam brush -- the Wooster's sold at Lowes are excellent and very inexpensive. Stir (don't shake) the poly and thin it with mineral spirits if that helps.

Apply about 4 coats, waiting about 24 hours for each one to dry. Sand *very* lightly between coats with 400 grit.

After the final coat wait a few days for a full cure. Then, if you want to knock down the plastic-like look, rub the new finish with 0000 steel wool and some good quality wax. It will make it silky smooth but not glossy.

If you're careful and patient, you'll have a really professional looking finish. I used this protocol on some beaten-up kitchen cabinets and the final result was simply wonderful. The striping/sanding is a pain but everything else is pretty quick and easy to do right.

Card scraper did the job for me last set of kitchen cabinet fronts I was paid to strip. Prepare to file the edge every 2 minutes (no hook needed), but even then, it's faster than anything short of a hot lye bath.

Use poly or alkyd enamel paint. Prob with linseed is it takes about a year to fully cure, during which time it'll absorb whatever cooking fumes you have floating about your kitchen.