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Old 15th August 2010, 12:35 AM   #1
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Default Quickie woodworking question! With bonus shellac question...

Sanding off a table covered with paint and so on, going to shellac it.

Starting with 50 grit and removing a lot of material. Planning to do a finish with 120 grit...

Q1: do I need an intermediate step?
Q2: Is 120 fine enough?

My dad who did the work table originally gave it an almost glasslike shellac finish, which I'd like to duplicate.

By the way, after a set of first passes the color is uneven, maybe because the wood surface has become somewhat uneven over time and/or maybe I haven't sanded through every last bit of the old finish...I fear that will persist, so would a pass with 80 grit help? Or do I just need to grind down some more with 50 grit?
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Old 15th August 2010, 01:56 AM   #2
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Best answer depends somewhat on the wood species, finish & intended use. The 50 grit you are starting with is fine for taking out large imperfections, but you need to use care to work toward a flat surface as it is easy to end up with broad peaks & valleys. From there I would follow with at least 80 and 150 grits & you should vacuum thoroughly between grits.

150 is the lowest I would finish at for a utilitarian application. For high quality appearance I typically would continue up to 220 and end at 320, again vacuuming between grits. Sounds like a pain, but once you establish a flat and smooth surface at your lowest grit, the next steps will go pretty quickly. Also if you skip an intermediate grit you will need much longer sanding the next grit up to remove the scratches from the coarser grit. Happy sanding!
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Old 15th August 2010, 04:58 AM   #3
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That makes sense-thanks. I think I already have some peaks and valleys unfortunately-as some areas were more covered with gunk than others, and the wood was not flat in the first place.

In that case, anyone have good advice on how to get all of the surface smooth? (Not necessarily flat, but hopefully all smooth).
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Old 15th August 2010, 12:04 PM   #4
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Not surprising, the natural tendancy is to focus your sanding on the areas that have the deepest damage. The paradox is that you have to remove the most material in undamaged areas as you bring the whole surface down enough to get to a flat plane that is just below the deepest damage.

First I would use a large diameter random orbit sander & keep it moving across the surface with overlapping strokes covering first across & then along the length of the surface. A belt sander can work faster but takes much more care to avoid digging in along the edges of the belt. Avoid the temptation to linger in the low spots with obvious damage.

One trick is to periodically (every 10 minutes or so) take a pencil and scribble a broad pattern over the whole surface. As you sand using the above technique the areas that get cleaned off 1st will be the high spots where the most sanding is needed & the areas that the pencil marks persist are the low spots where you want to avoid lingering. So what you want to see as you work is the area free of pencil scribbles growing and the area where the scribbles persist shrinking until they merge into a flat plane. All this is on your coarsest grit. Then as you move up in grits use the same sanding technique (pencil marks no longer needed) and the plane will be preserved.
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Old 30th August 2010, 04:08 PM   #5
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This greatly depends on the species under the paint. I would graduate down in much smaller steps with paper. Something like this 50,80,120,150,220.....then hand block with the grain with 320. The first two should remove all of the previous finish and give you a pretty flat surface, using the pencil technique described above. The latter four should only be used to remove the etching from the previous grit....not to remove imperfections or flatten. Of course we could be of more help if we knew what kind of wood, the sander you'll be using, and the size of the table. My best advice.... resist the urge to push down and hover over imperfections, let the paper and the weight of your sander do all the work. Note: Denser and more resinous woods will generally be reluctant to absorb the first two coats of shellac, if finish sanding past 220. There is such a thing as too smooth with certain wood species. Good luck.

Last edited by steviedon; 30th August 2010 at 04:18 PM.
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Old 30th August 2010, 04:25 PM   #6
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If you intend to sand the paint off, be prepared for a lot of grief. Paint stripper can save you tonnes of time. You'll get to bare wood in almost no time.

The sanding has been already covered above, but you don't mention a stain. Depending on the type of wood, it might or might not have a nice character without a stain. I prefer water based stains with shellac. You also don't mention what kind of shellac finishing you're planning to do. To me the most beautiful is french polishing. It's a bit of work to do it right but it has the most organic feel to it.
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Old 31st August 2010, 03:31 PM   #7
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Hmmm, I swear I had posted this, but maybe I was hallucinating.

The table is about 7'x1.5' and appears to be pine. Just a simple piece from Home Depot, looks like it's one of those where several boards are joined together.

I too too belatedly realized I could have simply turned over the top...or bought a new one, maybe for less than I'll end up spending on sanding belts and stuff! :-(

The belt sander is a 3x18" Ryobi. Some stuff is very penetrated, so this is turning into a LOT of work.

The finish...when my dad made the table he just stained it clear, it looked nice and shiny. I didn't realize there are different types of shellac finishing...do tell more.

AND...the sanding is not coming out smooth. Should I cut my losses, and just flip the board and start fresh with a smoother surface? If so, should I 220 with the belt sander, or will I get better results by hand?

Thanks!
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Old 31st August 2010, 06:37 PM   #8
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Hi head_unit.

If you do resort to paint stripper this stuff is fantastic (if it is available where you are).

PeelAway Poultic Paint Removal System

My house is 110 years old and was previously owned by the King of white gloss paint. I had to turn sideways to walk up the stairs the paint was so thick.

One application of the peel away stuff took us to clean wood. Also the backing paper means much less mess and burning fingers compared to nitromors and the like.

John
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Old 31st August 2010, 06:55 PM   #9
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A few dents/scratches give a finished table character; many dents/scratches look ugly. If that's the case, your idea of turning it over might work, if the other side isn't itself with marks from the connection to the legs.

If you decide to use paint stripper, which is I'd definitely recommend, you'll have to use a spatula to remove the gunk once the stripper has melted the old coating. But you'll have to do it carefully so you don't mark the wood surface, since pine is soft.

Applying a nice stain to pine is harder to do beautifully, and the wood needs to be sealed. Probably simpler to leave it natural colour.

Google french polishing if you want to know more about it, since it's not a procedure that's easy to explain in a few words. It can only be done, as far as I know, with real shellac, not with polyurethane. I avoid using anything other than shellac because of the awful smell of chemicals. But a shellac surface will not provide the protection a polyurethane treated surface provides.
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Old 31st August 2010, 07:59 PM   #10
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Head unit,

Flipping the top is certainly an option depending on what you find underneath. Another option is to get 3 nice 8' pine 1x8s (3/4 by 7-1/2 actual) & glue them up into a replacement top. You could also contact a local woodworking shop to see what they would charge to pass the top through a wide belt thicknessing sander once the paint is off and you have a clean surface. Whatever you decide you should definitely give the belt sander a rest & invest in a good 5" to 6" random orbit sander. In my collection of handheld sanders I have:

1 belt sander
2 oscillating pad sanders
2 random orbit sanders

The random orbits are used for 99+% of the sanding, the oscillating pads mostly sit idle and the belt is used very-very infrequently. Random orbits are the best option for fast sanding with good control. As you have experienced, it takes a lot of care and technique to get a flat surface with a belt sander.
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