Jieldé lamp: what finish to use?  

Hi all,
Some time ago I came into possession of a Jieldé working lamp.
I was visiting an uncle of my girlfriend, who has a metal workshop, mainly for working cars and trucks.
It's his hobby and over the years things have piled up. When I went there, my eye fell on some very rusty working lamps that were thrown on top of some cabinets. The only interesting one was a Jielde and with some effort of my mother in law I got it for free, promising I wouldn't sell it.
I was very happy offcourse, as here in Belgium these are very hard to come by (in France you can find these on every marché aux puces, but they know the price). The only problem: it was missing it's socle and the head was badly scuffed and dented.
It had also received several layers of paint and was missing half of the original green laquer.
I scourced a donor lamp, missing it's arms, here in Belgium. Ordering replacement parts seemed very expensive.
Connected everything together and...it worked!
I found a good product to remove the paint and I'm now finishing of with a rust-remover.
I would like to keep it in its vintage condition and avoid a newish-chrome industrial look.
This is what I've got right now, there some slight rust and dirt (patination?) left. I would like to seal this in to avoid further deterioration or rust.
Is this possible and wich product would you suggest?
It has to be heat resistant (lamp head), transparant.
Thanks!