spit coat of shellac to guide final top shaping?

[Brian Evans]

I'm close to a final shape on the outside of the redwood top I am making. I'm finding it really hard to see the shape - it's well disguised by the grain lines and the curl. Does anyone ever gloss the top up a bit with a thin coat of shellac to see the curves better? Understanding that I will do the final shaping after the box is built, and I will probably put a coat on to protect the top while I carve the inside shape. Any other ideas to see the shape better?

Thanks, Brian

[Barry Daniels]

Best way to see the shape is to turn off the overhead lighting and use a lamp to light the instrument from the back side. Place the light at the same elevation as the top. Stand back a bit and try not to focus on the fine details but the overall shape of the top. Also, using your sense of feel in your fingertips can act as a guide to shape.

[David King]

Try applying a strip of clear packing tape to see what a gloss finish can reveal. As Barry says your fingers are the best measuring tools you have.

[Michael Lewis]

The adhesive on the tape can pull bits of wood out of the surface. I would recommend a coat of shellac or a sealer before using tape on raw wood.
I used to use unfrosted incandescent bulbs for a bright light to cast clear shadows at a low angle. I guess LEDs are probably the best alternative now. You need clear bright light at a low angle so it casts "long" shadows. And you do need a darkened room for best results.

You can 'teach' your hands and fingers to feel some things that you have difficulty seeing.

I think you have your hands full getting the figured wood to conform to a smooth curve. Once you get the shape close, do the rest with sanding forms. (you'll have to make your own so they conform to the shapes you want) You probably already know that figured wood seems to be softer in some areas of the figure and harder in others. This creates a challenge to master the surface. I think you will learn a lot.

[David King]

Yeah i forgot we were talking about redwood so test any tape first. That stuff can be a shade less durable than styrofoam.

[Michael Lewis]

The idea of applying a glossy coat or two for revealing 'irregularities' in the surface is apt. Most times when I begin finishing a carved instrument the first couple coats get sanded off to make the final 'adjustments' that are so hard to see otherwise. I find shellac to not sand so well, and prefer an easier sanding material for this step. Regular lacquer is easier to sand than shellac, and I think it's preferable even if I have to sand it all off before building the finish coats.