Zahid Naqvi
05-19-2008, 2:47 PM
I'm so excited to finally get a handle on any finishing technique I just had to share. Most of my close WWing friends know that this is the aspect of WWing I hate the second most (sanding is #1). I read Jef Jewitt's "great wood finishes" several times, that and most of the opinions on the web suggest the regimen of sanding from 320 or 400 grit to gradually work through grits and culminating in pumice and rotten stone (for glossy finish). That just sounded too tedious and involved to me, remember this is not my favorite part of WWing.
As usual I call my go to guy, Dennis Peacock, no luck he's MIA. So I go through my list of book marks to see if I can find any thing that does not require two hours of sanding and rubbing. Then I discover this page (http://www.frets.com/FRETSPages/Luthier/Technique/Finish/FrenchPolish/frenchpolish1.html). It's still longer than what I had hoped for but does not involve pumice and rotten stone and seems like it can be done in one session. So here is what I did, in case someone can make any use of it.
1. I gave up on brushing shellac after the first coat, I just couldn't get even enough coats, despite using an artists brush. I switched to padding and it worked great, perhaps because that is what I am used to for most other finishes I have used in the past. So I built up about 7 coats of 1-1/2 # cut padded shellac applied over 3 days and let it cure for abour 4 days.
2. I see several brush marks from the first coat and some spots where there are drips, plus some other minor blemishes. Since I have a thick enough coat I start with 320 grit sand paper. Backed with a wooden block I sand the surface enough to get an even scratch pattern. There are still some "low spots" I can't get to because if I try to get to them I know I will completely sand-off the shellac from the adjoining areas. I know I will get these at the end so nothing to worry.
3. Next is an even lighter sanding with 400 grit, using hands for backing. This paper clogs much faster so I change sandpaper frequently.
4. Next up 800 grit, again using hands for backing. This doesn't create much dust but I can see the pores starting to show up due to the white shellac powder getting into them.
5. I clean up the board with mineral spirits.
6. This is followed by a good rubdown using a 0000 steel wool pad, using mineral spirits as lube.
7. followed by another cleanup using mineral spirits.
At this point the wood surface is acceptable at a very dull satin, but still has a "dry look" to it, you how how if you sand a finish and even though it is squeaky clean it still looks like there is still some dust on it because of the scratch pattern of sanding. Time for the French polish thing.....
8. I make a new pad for the polish, load it from the inside with the same 1.5 cut shellac, and dab it a few time on a scrap board to make sure the shellac is not dripping. Now I focus on a small 2 ft long section, drop a couple of drops of mineral oil and spread it our with my fingers and start doing the air plane take off and landing thing with the shellac pad. The first few stroker/rubs feel slippery, but then I start falling into a rhythm. After a while I star moving towards the section of the board that wasn't oiled, expecting that the pad will start catching it because of the lack of oil. But I guess the pad must have picked up all the oil from the previous section because I never feel a difference in the surface friction. As I apply the shellac I can see the evaporating trail but after a while the evaporating trail starts to disappear, I thought I had dried out the pad, dab it on the scrap, it still has shellac. So I keep doing the airplane landing and takeoff thing, with a slightly increased speed. The "wet look" is persisting though, I am starting to think I will have to clean off this oil because the pad is not picking it up. After going at it for about 5-7 mins on a stile 4.5" by 3ft. I stop and touch the surface to determine how much oil is still present, and that's when I realize the surface it not wet it is "glossy" :D:D
The board is shining so well it looks like it is wet. I can read the label of a bottle from the reflection.
This is so much easier than I thought it would be, I just can't believe how good the finished board looks. So much for pumice and rotten stone :rolleyes: I think I have found my regimen for "french polish"
Here are a few lessons learned or mistakes made, depending on how you look at it.
1. This is one of those duh! things, don't use the solvent you mixed with the finish as the cleaner. That is, if you are using DNA to thin/mix shellac do not use it for post sanding cleanup.
2. If you build a thick enough layer of finish the quality of the post application surface is not that critical, because the sanding will take care of all application marks.
3. Always load the shellac pad from the inside, never "dip" it in the shellac, it dries too fast and the first time you touch the pad on a board it will always leave a puddle.
4. Thin coats dry faster but you can apply more coats per session. Thick coats dry slower but you need fewer coats.
5. The automobile rubbing compound is crap for WWing, the wax gets lodged in the pores and looks horrible and is a pain to cleanup. I think any waxy polishing compound would have to be color matched with the wood to make sure it is not visible when applied on a board that does not have the pores filled.
6. No matter what you read and learn from others, there is no substitute for personal experience/experimentation.
Another thing I can mark off my "to learn" list
As usual I call my go to guy, Dennis Peacock, no luck he's MIA. So I go through my list of book marks to see if I can find any thing that does not require two hours of sanding and rubbing. Then I discover this page (http://www.frets.com/FRETSPages/Luthier/Technique/Finish/FrenchPolish/frenchpolish1.html). It's still longer than what I had hoped for but does not involve pumice and rotten stone and seems like it can be done in one session. So here is what I did, in case someone can make any use of it.
1. I gave up on brushing shellac after the first coat, I just couldn't get even enough coats, despite using an artists brush. I switched to padding and it worked great, perhaps because that is what I am used to for most other finishes I have used in the past. So I built up about 7 coats of 1-1/2 # cut padded shellac applied over 3 days and let it cure for abour 4 days.
2. I see several brush marks from the first coat and some spots where there are drips, plus some other minor blemishes. Since I have a thick enough coat I start with 320 grit sand paper. Backed with a wooden block I sand the surface enough to get an even scratch pattern. There are still some "low spots" I can't get to because if I try to get to them I know I will completely sand-off the shellac from the adjoining areas. I know I will get these at the end so nothing to worry.
3. Next is an even lighter sanding with 400 grit, using hands for backing. This paper clogs much faster so I change sandpaper frequently.
4. Next up 800 grit, again using hands for backing. This doesn't create much dust but I can see the pores starting to show up due to the white shellac powder getting into them.
5. I clean up the board with mineral spirits.
6. This is followed by a good rubdown using a 0000 steel wool pad, using mineral spirits as lube.
7. followed by another cleanup using mineral spirits.
At this point the wood surface is acceptable at a very dull satin, but still has a "dry look" to it, you how how if you sand a finish and even though it is squeaky clean it still looks like there is still some dust on it because of the scratch pattern of sanding. Time for the French polish thing.....
8. I make a new pad for the polish, load it from the inside with the same 1.5 cut shellac, and dab it a few time on a scrap board to make sure the shellac is not dripping. Now I focus on a small 2 ft long section, drop a couple of drops of mineral oil and spread it our with my fingers and start doing the air plane take off and landing thing with the shellac pad. The first few stroker/rubs feel slippery, but then I start falling into a rhythm. After a while I star moving towards the section of the board that wasn't oiled, expecting that the pad will start catching it because of the lack of oil. But I guess the pad must have picked up all the oil from the previous section because I never feel a difference in the surface friction. As I apply the shellac I can see the evaporating trail but after a while the evaporating trail starts to disappear, I thought I had dried out the pad, dab it on the scrap, it still has shellac. So I keep doing the airplane landing and takeoff thing, with a slightly increased speed. The "wet look" is persisting though, I am starting to think I will have to clean off this oil because the pad is not picking it up. After going at it for about 5-7 mins on a stile 4.5" by 3ft. I stop and touch the surface to determine how much oil is still present, and that's when I realize the surface it not wet it is "glossy" :D:D
The board is shining so well it looks like it is wet. I can read the label of a bottle from the reflection.
This is so much easier than I thought it would be, I just can't believe how good the finished board looks. So much for pumice and rotten stone :rolleyes: I think I have found my regimen for "french polish"
Here are a few lessons learned or mistakes made, depending on how you look at it.
1. This is one of those duh! things, don't use the solvent you mixed with the finish as the cleaner. That is, if you are using DNA to thin/mix shellac do not use it for post sanding cleanup.
2. If you build a thick enough layer of finish the quality of the post application surface is not that critical, because the sanding will take care of all application marks.
3. Always load the shellac pad from the inside, never "dip" it in the shellac, it dries too fast and the first time you touch the pad on a board it will always leave a puddle.
4. Thin coats dry faster but you can apply more coats per session. Thick coats dry slower but you need fewer coats.
5. The automobile rubbing compound is crap for WWing, the wax gets lodged in the pores and looks horrible and is a pain to cleanup. I think any waxy polishing compound would have to be color matched with the wood to make sure it is not visible when applied on a board that does not have the pores filled.
6. No matter what you read and learn from others, there is no substitute for personal experience/experimentation.
Another thing I can mark off my "to learn" list