Post by wisardd1 on Jan 5, 2010 17:13:41 GMT -6
Working on a clock that has some similarities to a metronome. So far I have come acrossed a Benjiman Moore oil paint and lots of laquer. This is one: any thoughts or suggestions
OK. About that "Piano Finish" we hear so much about. There are two distinctly different finishes being talked about here. The traditional "hand-rubbed" piano finish and the more recent "high-gloss" finish. The high-gloss finish is polyester -- a plastic. Since we don't care for the look that this finish gives to pianos we don't use it and I'm not qualified to comment on its application.
The hand-rubbed finish is usually nitrocellulose lacquer. This material is quite easy to work with, just remember that it is extremely flammable -- explosive even -- so take care. It also stinks and it's not real good for your insides. You will need lots of ventilation, both to reduce the fire danger and to reduce the wear and tear on your lungs and your brain.
The following procedure works for both clear and colored lacquer finishes. If you are using black, I'd suggest using an automotive acrylic lacquer. Especially if you want a high-polish finish. Traditional nitrocellulose tend to look a bit blue or gray when polished out.
Surface preparation. All surfaces must be sanded to a dead flat finish. We dry sand with an open coat aluminum oxide paper -- not stearated -- starting (usually) with 120 grit and working up through every grit to 320. When sanding flat surfaces the paper is always used with a firm rubber sanding block. All surface dings, scratches, blemishes, etc., are filled or fixed after the first sanding with 120 grit. All imperfections must be fixed before either the stain or the first coats of finish are applied. (The obvious exception being with a black finish which can be patched at any time.) After the final sanding we "break" the edges to a nice uniform radius using 220 or 320 grit paper backed up with sensitive fingers.
If the wood is an open pore wood and the finish is to be closed pore, the next step is to pore fill. Pore filler is a silica base material that is thinned to approximately the consistency of heavy cream and brushed on both with and across the grain. Pore fillers can either be applied in their natural color -- a light creamy tan -- or stained to accent the pore texture of the wood. Once the pore filler is partially dry (the surface is just dull) it is wiped or scraped off across grain. A tiny amount of pore filler will be left in the open pores of the wood leaving the surface quite flat. Allow the remaining pore filler to dry for at least 24 hours and sand the surface lightly with 220 grit and 320 grit dry paper.
If the wood is to be stained, now is the time to do it. We also stain the wood of pianos that are going black. It helps later when Johnny runs into the leg with his new toy truck and chips the finish. There are a variety of different types of stains available. Books have been written on the subject. For most amateurs the selection is going to be somewhat limited to what can be found at the local HomeBase or hardware store. These are usually oil based or water based stains. All I can say here is to follow the directions on the can.
After the stain is dry apply the first coats of finish material. You can use sanding sealer if you wish, we do not. Sanding sealer is simply lacquer with some additives blended in to make it easier to sand. If you've done your prep work well you won't have to do that much sanding anyway and lacquer without the added stearates bonds better and is more durable.
(Note: If I were putting a black finish directly over MDF or particleboard, I'd first spray on a coat of black or dark gray automotive primer. These are very heavy bodied filling primers designed to fill in rough metal work and leave a fairly smooth sanding surface. It might take two coats.)
We spray three coats of lacquer straight over the stained wood surface. Allow this to dry (we allow 24 hours) and wet sand with 320 grit wet-or-dry paper on a firm rubber sanding block. Don't over do this. You're only trying to knock off the high spots here. Lacquer chemically bonds to lacquer so you don't need to "rough-up" the whole surface. You're getting rid of raised grain, dust particles, etc. (You didn't get any runs in the vertical surfaces, did you? If so, sand them out also.) What you don't want to do is sand through your nice new surface into the stained wood.
Spray three more coats of lacquer on the surface. You're more experienced now so you won't get any more runs, right? Again, allow 24 hours of drying time and wet sand with 400 grit paper still on a firm rubber block. This time you want to sand the surface pretty well flat. Always sand with the grain and be extra careful around the edges.
Spray on three more coats of lacquer. This time let the surface dry for at least three days. Wet sand, starting with 400 grit paper and working through 500, 600. If this is to be a "hand-rubbed" finish stop here. The final rub is most easily done with plastic wool sheets (the white kind without any built in abrasive) and pumice or rottenstone. If you can't easily find these, good old Ajax will work. So will automotive rubbing compound.
If the finish is to be more highly polished, continue sanding through at least 800 grit. Now switch to polishing compounds. We use 3M, but McGuires (sp?) is more commonly available. Visit your local auto paint store. There are about a million different compounds available and I don't even pretend to keep up with them. Find someone at the store who knows what they sell -- if you can -- and ask. The final polish will be done with a random orbital buffer. These might be available for rent. Otherwise, check Sears and/or head back to your local auto paint store.
The above is not intended to answer all of your questions about finishing wood. It's a complicated subject, but it's not an impossible subject for one who has already figured out how to build a speaker system. If all of this whets your appetite for fine finishing, might I suggest two excellent books:
Understanding Wood Finishing by Bob Flexner (Rodale Press), and
Spray Finishing by Andy Charron (The Taunton Press).
Achieving a fine finish on your work is not all that difficult. It does require some knowledge of the the materials you use and the proper techniques used to apply them. And some patience. Good luck.
Del
Del Fandrich
Piano Designer & Builder Hoquiam, Washington USA
dale
OK. About that "Piano Finish" we hear so much about. There are two distinctly different finishes being talked about here. The traditional "hand-rubbed" piano finish and the more recent "high-gloss" finish. The high-gloss finish is polyester -- a plastic. Since we don't care for the look that this finish gives to pianos we don't use it and I'm not qualified to comment on its application.
The hand-rubbed finish is usually nitrocellulose lacquer. This material is quite easy to work with, just remember that it is extremely flammable -- explosive even -- so take care. It also stinks and it's not real good for your insides. You will need lots of ventilation, both to reduce the fire danger and to reduce the wear and tear on your lungs and your brain.
The following procedure works for both clear and colored lacquer finishes. If you are using black, I'd suggest using an automotive acrylic lacquer. Especially if you want a high-polish finish. Traditional nitrocellulose tend to look a bit blue or gray when polished out.
Surface preparation. All surfaces must be sanded to a dead flat finish. We dry sand with an open coat aluminum oxide paper -- not stearated -- starting (usually) with 120 grit and working up through every grit to 320. When sanding flat surfaces the paper is always used with a firm rubber sanding block. All surface dings, scratches, blemishes, etc., are filled or fixed after the first sanding with 120 grit. All imperfections must be fixed before either the stain or the first coats of finish are applied. (The obvious exception being with a black finish which can be patched at any time.) After the final sanding we "break" the edges to a nice uniform radius using 220 or 320 grit paper backed up with sensitive fingers.
If the wood is an open pore wood and the finish is to be closed pore, the next step is to pore fill. Pore filler is a silica base material that is thinned to approximately the consistency of heavy cream and brushed on both with and across the grain. Pore fillers can either be applied in their natural color -- a light creamy tan -- or stained to accent the pore texture of the wood. Once the pore filler is partially dry (the surface is just dull) it is wiped or scraped off across grain. A tiny amount of pore filler will be left in the open pores of the wood leaving the surface quite flat. Allow the remaining pore filler to dry for at least 24 hours and sand the surface lightly with 220 grit and 320 grit dry paper.
If the wood is to be stained, now is the time to do it. We also stain the wood of pianos that are going black. It helps later when Johnny runs into the leg with his new toy truck and chips the finish. There are a variety of different types of stains available. Books have been written on the subject. For most amateurs the selection is going to be somewhat limited to what can be found at the local HomeBase or hardware store. These are usually oil based or water based stains. All I can say here is to follow the directions on the can.
After the stain is dry apply the first coats of finish material. You can use sanding sealer if you wish, we do not. Sanding sealer is simply lacquer with some additives blended in to make it easier to sand. If you've done your prep work well you won't have to do that much sanding anyway and lacquer without the added stearates bonds better and is more durable.
(Note: If I were putting a black finish directly over MDF or particleboard, I'd first spray on a coat of black or dark gray automotive primer. These are very heavy bodied filling primers designed to fill in rough metal work and leave a fairly smooth sanding surface. It might take two coats.)
We spray three coats of lacquer straight over the stained wood surface. Allow this to dry (we allow 24 hours) and wet sand with 320 grit wet-or-dry paper on a firm rubber sanding block. Don't over do this. You're only trying to knock off the high spots here. Lacquer chemically bonds to lacquer so you don't need to "rough-up" the whole surface. You're getting rid of raised grain, dust particles, etc. (You didn't get any runs in the vertical surfaces, did you? If so, sand them out also.) What you don't want to do is sand through your nice new surface into the stained wood.
Spray three more coats of lacquer on the surface. You're more experienced now so you won't get any more runs, right? Again, allow 24 hours of drying time and wet sand with 400 grit paper still on a firm rubber block. This time you want to sand the surface pretty well flat. Always sand with the grain and be extra careful around the edges.
Spray on three more coats of lacquer. This time let the surface dry for at least three days. Wet sand, starting with 400 grit paper and working through 500, 600. If this is to be a "hand-rubbed" finish stop here. The final rub is most easily done with plastic wool sheets (the white kind without any built in abrasive) and pumice or rottenstone. If you can't easily find these, good old Ajax will work. So will automotive rubbing compound.
If the finish is to be more highly polished, continue sanding through at least 800 grit. Now switch to polishing compounds. We use 3M, but McGuires (sp?) is more commonly available. Visit your local auto paint store. There are about a million different compounds available and I don't even pretend to keep up with them. Find someone at the store who knows what they sell -- if you can -- and ask. The final polish will be done with a random orbital buffer. These might be available for rent. Otherwise, check Sears and/or head back to your local auto paint store.
The above is not intended to answer all of your questions about finishing wood. It's a complicated subject, but it's not an impossible subject for one who has already figured out how to build a speaker system. If all of this whets your appetite for fine finishing, might I suggest two excellent books:
Understanding Wood Finishing by Bob Flexner (Rodale Press), and
Spray Finishing by Andy Charron (The Taunton Press).
Achieving a fine finish on your work is not all that difficult. It does require some knowledge of the the materials you use and the proper techniques used to apply them. And some patience. Good luck.
Del
Del Fandrich
Piano Designer & Builder Hoquiam, Washington USA
dale
