Official Luthiers Forum!

I was wondering whether you sanded your tops prior to finishing or scraped them. I am working on my first, and it seems like sanding the sitka spruce leaves wavy lines that I don't really like. Do you scrape to get rid of these lines or do I just have a strange top? Thanks.

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Aaron Craig

Scraping softwoods can be very difficult. Do you use a block? I usually sand cross grain with a flat block, and along the grain for the last strokes.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

I do have a block and I can try that. Thanks.

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Aaron Craig

What Laurent said...
I wipe the parts with naptha & check closely for scratches before spraying. Hold the parts up to a strong light at a low angle & check while the naptha is still wet.
I only sand across the grain on softwoods. Always with the grain on hardwoods.

Also, don't use much (or any) pressure when sanding. Let the sandpaper do the work.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

I've find the best sanding block for surface prep to be a wood block with 1/8" layer of cork glued on.

Steve

I see two folks mention sanding across the grain for the top,have never tried that approach. I wonder what is the benefit...?
Tom

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A person who has never made a mistake has never made anything!!!

Large variation in the hardness of the slow and fast growth lines of the annual growth rings. Sand with the grain and the softer part will sand faster, leaving a corduroy effect. Across the grain doesn't.

Heavy scraping tends to create a specific corduroy texture which will look distinct from a sanded surface with a thin finish such as shellac. Most people would frown at it, while in violin world it is the other way around - a smooth sanded surface is considered the sign of cheap instrument.

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Build log

I prefer to glue the paper to the block for finish sanding. Rubber cement allows changing the paper, or get adhesive backed paper, or use doubled sided carpet tape.