surface should look glossy without any dry spots, but do not apply too much at a time to the point where it puddles or runs. The great thing about shellac is that in addition to protecting the surface, it also acts like a coat of glue bonding everything together. You might want to apply several coats depending upon how it looks. Apply a second coat of shellac before doing any sanding so as not to damage the original finish. After the second coat has dried, than lightly sand it with some 600 grit sand paper to smooth and blend the old and new surfaces. If you need to level or smooth the surface, then you could go as low as 320 grit. Try not to cut through the shellac into the original finish, but if you do, just apply another coat of shellac. After the last coat of shellac has dried overnight, you could lightly rub it with 0000 steel wool to further smooth and blend everything. I like to follow up with a light coat of Renaissance wax to bring up the soft sheen after it has been dulled by the steel wool. 2. Gluing Up a Tabletop with Unibond 800: I was reading about Unibond 800 and saw that it contains formaldehyde and that people recommend using a respirator when working with it. Is that what you do and how dangerous is it? Is there a non-formaldehyde glue that you would recommend that has similar results? We talked about bringing the table top to get it drum sanded. Is that done before any final scraping and sanding? Nick David's Answer: To protect myself from the formaldehyde in the Unibond 800 glue, I wear a charcoal respirator. 3M has a low-maintenance half-mask organic vapor P95 respirator assembly. I try to keep the doors open for ventilation and/or use a fan, but basically I rely on the charcoal respirator to protect my lungs. I have been using this type of glue for over 30 years, and the only “damage” I’ve noticed is that people tell me that I look “well preserved” for my age (61) ha ha ha ha. I don’t know of any other glue that works as well that is non-toxic. You could use yellow glue, but it won't be as strong as the Unibond, plus you will only have 10 minutes or less to get it clamped up. The polyurethane glues are good, but there is the foaming out situation that occurs, and they still simply are not as strong as the Urea resin glues. After the glue up of the table top, I would scrape off any squeeze out, then take it to a shop and have it drum sanded to as high a grit as they offer—which would most likely be 180 or possibly even 220 grit. After that, I would use a card scraper to remove any scratches left by the drum sander. If someone isn’t skilled or comfortable with the card scraper, then I recommend using a random orbit sander. Festool makes one of the best, which does a great job of removing the coarse scratches and smoothing and blending the surface.
July-August, 2013
You need to keep checking the surface with a light to look for surface imperfections. This is referred to as observing the surface in the “raking light.” Translation: place a strong light source on the opposite side of you and the table top. As the light rakes across the surface of the wood and you move your head into position to examine each square inch of the surface, any imperfections will become exaggerated by the light reflecting off of it, thereby illuminating it. Take a piece of chalk and draw a circle around areas that need more sanding. I also like to use a block of wood that I have run over the jointer to create a dead flat surface and attach some sand paper to it and hand sand with the direction of the grain to make sure that the top is flat and doesn’t become slightl ???????????????????????5?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????Q????????????????????????????????????????????????????????????????????=????????????????????????????????????????????????????????????????????Q????????????????????????????????????????????????????????????q????????????????????t?????????????%?????A????????$???????????????????????????????????????????????????????????????????????????????????$?????????????????????? ?????????????????$???????????????????????????????????$???????Q??????????????????????????e??????????????????????????????????????????????????????????????????????????????????????????????????????????????!???????????????????????????????????????????$???????????????!?????????????????????????????????????????????????????????????????????????$????????????????????????????????????????????????????e????????????????????????????????????????????????Q??????'?e?????????M????????????????$????????????????????????????????????????????5??????????????????????????????????????????????????????????????????Q??????????????????????????????????????????????????????????????$?????????????????????????????????????????????????????????????????e??????????????????????????????????????????????????????????????????????????????????????????????5??????????????????????????????????????????????????????????????????????????????????M?????????????????????????????????????????????????????????????????$????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????5?????????????????????????????????????????????)A??????$()]???????]???$((0