After a nice stain job,I would like to render the wood shiny.
Can shellac or a similar be used without changing the wheight?
Any help please. Don

Anything added to the wood will add weight. How much is acceptable, is your choice.

I've only worked with Balsa for model airplane building when I was a kid, but it seems to be a fairly porous wood. This means it will soak up some finishes like a sponge. I'm not sure without experimenting, but a wood sealer before the varnish may minimize that.

Thank you Mr. Baker

If you're going to be using shellac,you should be applying it with a rubber not a brush.
This is reasonably easy to do on straight flat areas,but,due to the reversable nature of shellac,becomes a bit trickier on more ornate areas.
Using a rubber instead of a brush,brings up the finish a lot faster using less material,as a lot of the time you're applying very little but using it as a burnishing medium working the previously applied polish(shellac)
If you can get your hands on pale polish,rather than the more standard button polish,it will give a more natural hue to the finish rather than the yellow tinge that button polish gives.
The amount of polish used will be tiny and the weight negligable.
A rubber is basically some cotton wool/wadding,wrapped into a pear shape with some lint free fine cotton cloth.Obviously it has to have one flat face which you use to apply the polish.
Another way would be to apply a few coats of polish,then finish with wax and a fine wire wool(000 grade)
In this case,the finish hasn't got to be hard wearing,as the substrate is so soft any finish applied will make no difference to its durability.
Ray.

I have used Minwax Polyurethane sealer successfully on balsa wood. Of course I was not so concerned with added weight, so I cannot really comment on that.

Regan

When I looked at Ray's profile and noticed his occupation, it made me wish I knew how to speak English so I would know what the heck he was talking about.

Lord, I feel so inadequate some days...

Michael,if you heard me talk with my broad Nottingham accent,you'd have less of a clue.
I'll keep trying for everybody though.
Cheers,Ray.

Hi Ray,
Thank you for the feed back sir.
Question:
If I used a spray clear coat shine?(spray can)

So if understand it, instaed of using a standard brush, I would instead use a spunge brush or a rolled up cotton wad to pass along the wood.
Correct me please.

Don,I'll try and get a few pictures up for you,it may be easier to follow.
Ray.

Thank you Ray. Very kind of you.

I made a dancing cane out of balsa wood ... first painted it, and then a coat of polyurethane. Weight increase was minimal.

-JoeJoe