Varnish

A good quality single pack urethane will do a good job. Although much slower to harden than 2 pack urethanes they eventually go quite hard. The only problem you may have is matching gloss levels with the old doors. You can buy a matting gel to stir into the varnish to reduce gloss.

I always simply wipe (paint) over with Penatrol using a a wad of Magic eraser or a small foam brush. allow a day and a half to dry.
PeteS

Hi Barrie & thanks to Mick for dobing me in!

Firstly Barrie if your van was purchased new and you or Daph have not used a silicon based polish on them the job is relatively easy.

Initially I did one door and it dried cloudy and on consultation with the Chair man at the Quorn Muster my doors had probably been polished with a silicon based polish ( previous owner) resulting in me having to sand back each door.

Once that was done I used a satin estapol and the doors and drawers came up a treat. A light sand between coats. I did 3 coats.

I didn't finish the job at Quorn as they take a while allowing drying and sanding between coats.

Good luck, but a job worth doing.

Cheers
Noel