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Sanding Primer

Posted: Sat Mar 24, 2012 11:28 pm
by Nelson Palen
What do you guys and gals use to highight contour when doing fine carving and sanding on highly figured woods?
That would be flamed maple in this case and carving the transition ridge between a Florentine cutaway and the rest of the plate on an archtop.
I know that the autobody people use sanding primer for this purpose and seems like I've heard of some kind of temporary white coating that can be used on wood.
Just need something to show how true the profiled surface is and just in a small area.
Thanks

Re: Sanding Primer

Posted: Sun Mar 25, 2012 9:37 am
by John Meyers
I think I know what you are trying to do. If you want to see if you got all the spots sanded smooth with no high low or scratches left and want to do the way the auto body guys do, then you use a can of black spray paint. You just mist it over the area and sand back until it is all gone. Now this is what they do on a car and they do this after they have sprayed the primer and sanded it, so they can see if it ready for paint. I would say spray some kind of sealer or shellac first and sand that then spray the black so you will not stain the wood. Hope this helps.

Re: Sanding Primer

Posted: Sun Mar 25, 2012 9:57 am
by Dave Stewart
If I understand what you're after, for me, nothing shows up imperfections in a (carved) surface like late afternoon direct sunlight. I'm sure you've used this Nelson. You think it's pretty good, but then seeing it under low angle light it looks like the fender of an old Buick! I keep at this 'till satisfied, although still find a couple of spots I wish were better when the finish is all buffed up.

Re: Sanding Primer

Posted: Sun Mar 25, 2012 10:10 am
by John Hamlett
I wait until night time, turn off all the lights in the shop and use one swing arm lamp with a small bulb (compact fluorescent). By side-lighting in the dark room, I can see the contours. It's similar to Dave's sunlight "trick", but the single, small light source in the absence of ambient light works better for me.
Spraying color and sanding, I fear, would leave color in the pores.

Re: Sanding Primer

Posted: Sun Mar 25, 2012 12:39 pm
by Nelson Palen
This is the particular area. I can get by using the low light method but just thought there might be a quick trick of which I was unaware.
It's a little time consuming to get the transition ridge nice and uniform. I don't do a lot of Florentines but have some in the works currently.
I do this type of transition but am sure there are better methods out there.
Thanks for your input, guys. More is always better.
Edit: Forgot to mention that I carve the plate initially as if it was going to be a Venetian and then modify it to a Florentine.

Re: Sanding Primer

Posted: Sun Mar 25, 2012 1:25 pm
by Dave Stewart
Kind of reminiscent of the carving in F5 mandolins........ maybe check mandocafe. My first inclination is to heavily chaulk one side, right up to the ridgeline, & scrape the other side 'till things look balanced & centered, but that might be worth just what you paid for it!

Re: Sanding Primer

Posted: Sun Mar 25, 2012 2:14 pm
by Dave Stewart
ps.......I'd also make marks on a suitably curved scraper so it could be used in exactly the same positions on either side of the ridge & maintain symmetry in the recurves.

Re: Sanding Primer

Posted: Sun Mar 25, 2012 3:15 pm
by Nelson Palen
I like the scraper marking idea, Dave. I used the scraper to this point but it sure has to be sharp to avoid tearout on the figure. After a little more thinking about the white coating I mentioned in the first post, I believe that was a kind of masking material. It was to be brushed or sprayer on and then could be peeled off later. Don't know if it would work for this or not though.

Re: Sanding Primer

Posted: Sun Mar 25, 2012 4:37 pm
by John Hamlett
Dave Stewart wrote:Kind of reminiscent of the carving in F5 mandolins........ maybe check mandocafe...
Mandolin caving is, in fact, where my experience in this sort of thing comes from. If you check mandolin cafe, you will find that almost all of us side light our carvings.