Zhigel
Member
Hi, I have a question from this rookie. I have sanded a Purple Heart blank to 12,000 grit but I wanted to put a CA finish on it. First attempt! I saw where you should sand it to 400 to 600 grit. Have I sanded it too far to use CA?
Sanding prep for CA finish
- Thread starter Zhigel
- Start date
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I sand wood to 2,000 prior to CA, but I see and hear that many sand to 600. If I am applying CA to wood and acrylic/poly blanks, I will sand to a higher level, but not 12k. I don't think one can sand too far as long as the dimensions/diameter meets the hardware correctly. I an curious to learn what others think.
terry q
Member
Dan Masshardt
Member
No such thing as too far sanding for ca as far as grits. I don't think it adds any value sanding that high before ca but it shouldn't cause any problems.
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leehljp
Member Liaison
For the life of me, I do not understand the idea that you can sand too fine before adding finish. I have been working with wood in some format for 60+ years. In my early years I watched uncles and friends working with wood and have always enjoyed the smell of wood and sawmills.
Back to finishing too fine: If certain glues can stick a review mirror to glass, then no wood could be considered too smooth to make CA stick.
There are numerous circumstances in which improperly prepared wood or improper use of finish can and will cause the finish to peel, and the smoother, the easier it is to peel. But that is not from sanding too smooth.
HIGH END custom furniture makers do not sand in many cases but use hand scrapers which will be as smooth as anything higher than 600 - 1000.
Back to finishing too fine: If certain glues can stick a review mirror to glass, then no wood could be considered too smooth to make CA stick.
There are numerous circumstances in which improperly prepared wood or improper use of finish can and will cause the finish to peel, and the smoother, the easier it is to peel. But that is not from sanding too smooth.
HIGH END custom furniture makers do not sand in many cases but use hand scrapers which will be as smooth as anything higher than 600 - 1000.
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wouldentu2?
Member
Sand to remove scratches and create a smooth finish, save the extra sanding for the final CA finish.
jttheclockman
Member
First welcome to the site in case I did not welcome you. Second is you are wasting your time. A sanded piece of wood stops showing scratches after about 180 grit to the naked eye. I will usually stop at 220 grit in all my woodworking. Will take it a bit higher in some cases. The finish needs to attach to the wood and move with the wood. The finish is what you feel and see. This is where you need to concentrate your effort. But with that said, woods such a purpleheart are very oily woods and I suggest you wipe down with acetone before applying any finish. Let it dry before applying also. These are my thoughts.
robutacion
Member
The risk of too fine sanding in some woods is that the CA has a hard time to stick, not so much "stick" in the full extent of the word but more prevent the other coats to stick properly to that most critical first coat.
This first coat should be done with the finest CA you can find, in my view 600 grit sandpaper is smooth enough for the CA finish, wiping the wood with acetone will help the process considerably, the wood will absorb that first thin coat a lot better however, and where so many people make the big mistake is to not allow that first coat to dry/harden properly, don't sand that first coat and when possible give the blanks another 1 or 2 thing coats before you start with the thicker CA. Thicker CA may feel dry on the surface but is not underneath, multiple coats of this thick CA in a quick succession will create a thick "film" of CA that more often than not will detach from the wood, some woods are worse than others and some woods, you would be better to give it 2 or 3 coats of the thin CA and polish, more is not always better...!
Cheers
George
This first coat should be done with the finest CA you can find, in my view 600 grit sandpaper is smooth enough for the CA finish, wiping the wood with acetone will help the process considerably, the wood will absorb that first thin coat a lot better however, and where so many people make the big mistake is to not allow that first coat to dry/harden properly, don't sand that first coat and when possible give the blanks another 1 or 2 thing coats before you start with the thicker CA. Thicker CA may feel dry on the surface but is not underneath, multiple coats of this thick CA in a quick succession will create a thick "film" of CA that more often than not will detach from the wood, some woods are worse than others and some woods, you would be better to give it 2 or 3 coats of the thin CA and polish, more is not always better...!
Cheers
George
Zhigel
Member
I have denatured alcohol, would that work instead of acetone? Thanks you so much for the reply!
Jdubfudge
Member
When Ihve turned to thickness desired, I start with rather 100 or 150 depending how much I have to take down. I only sand the first grit with the lathe on at 500 rpms if I need to. Then hand turn the rest to 400. 320 and 400 are light sanding. Then blow it out with the air compressor and apply some BLO with a clean rag. I wait until it dries then apply 4 coats of thin CA and 4-5 coats of medium CA. Usually just a drop for each coat. Then start sanding with the pads. The first 3, I sand by hand. On the 4th on, I turn the lathe back on and work down to 12000. Then use the PlasticX for the final polish.
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Denatured alcohol is often recommended for this purpose. I use it on all of my blanks prior to finishing, help to clean out the grain. Just be sure to let it dry completely, which shouldn't take long.
I usually sand to 600, which is probably overkill. With segmented blanks where I wanted to avoid contamination I have put finish on with no sanding. Just use the skew to get a nice clean surface. I know a lot of guys just use the skew and never sand (I'm not that good with the skary skew...)
sanding
Some woods like ebony sanding with the lathe on is about the worst thing you can do.
Every wood working book in the world says don't sand across the grain.
Really what reason is there to sand wood with the lathe on ?
if the turner is good enough with a sharp skew or sharp cutter on the tool post or live cutter on the tool post.
Think of why you really need to sand, then try to minimized or eliminate the sanding process by using sharper tools .
Sand with the lathe off and with the grain, sand with 220 to 400 .
you only need a few passes .
If you start getting into segmenting different colors of wood cross sanding contamination is a giant issue ant the blank needs to besanded in certain directions and can only be done with the lathe off.
Over sanding is a giant issue ...
your loading the water pores with sanding dust , your changing the wood color ,dulling the wood and removing the woods color.
Loading the water pores with sanding dust leads to finish issues .
IMO Micro mesh is to be used on the finishes and acrylic , not bare wood.
I don't use it and I don't know any cuemakers who use it.
Not sure why mm is used so much in the pen turners world ..
buffing wheel for harder finishes, polishing cream for CA.
Some woods like ebony sanding with the lathe on is about the worst thing you can do.
Every wood working book in the world says don't sand across the grain.
Really what reason is there to sand wood with the lathe on ?
if the turner is good enough with a sharp skew or sharp cutter on the tool post or live cutter on the tool post.
Think of why you really need to sand, then try to minimized or eliminate the sanding process by using sharper tools .
Sand with the lathe off and with the grain, sand with 220 to 400 .
you only need a few passes .
If you start getting into segmenting different colors of wood cross sanding contamination is a giant issue ant the blank needs to besanded in certain directions and can only be done with the lathe off.
Over sanding is a giant issue ...
your loading the water pores with sanding dust , your changing the wood color ,dulling the wood and removing the woods color.
Loading the water pores with sanding dust leads to finish issues .
IMO Micro mesh is to be used on the finishes and acrylic , not bare wood.
I don't use it and I don't know any cuemakers who use it.
Not sure why mm is used so much in the pen turners world ..
buffing wheel for harder finishes, polishing cream for CA.
Woodchipper
Member
Could a tack cloth be used to clean the pores? Curious.
jttheclockman
Member
Not for what we do.
glennhayhurst
Member
I stopped by the dollar store to shop the other day and found denatured alcohol on the shelf. I was about to buy it for cleaning the blanks before applying the CA finish. I read the ingredients on the bottle and found that it was 50% water. Not good to put on wood just before you apply CA finish. The wood will absorb the water and the CA seals it in. This will give you a clouded finish UNDER the CA after a while. I have been using odorless mineral spirits instead. It evaporates quickly and does not contain any water that can cloud the finish.
budnder
Member
I think everybody settles into what seems to work for them, and there are many equal paths to a great finish. In my own experience, the particular CA you're using can have a big impact on what works for you. I use Satellite CA and here's what works for me:
Typically, prior to CA, I'll sand at most with 400. Depending on the material and the last pass of the skew, I may not sand at all. I just go by feel and visual inspection.
I do sand with 400 and then 600 between about every 3 coats of CA, to a total of about 9 coats. The first several are thin CA and the last several medium CA. I sand with the lathe off up and down the blank, until I can't visually see any marks. I do clean the blank after sanding with alcohol.
To finish it all off, I go wet micro-mesh through 12000, then Novus #2, then Novus #1. All of this is done on the lathe at lowish speed, though I crank it up for the Novus #2 and #1. After that, I sand off the tube ends vertically on a flat piece of 400 to remove any CA that extended beyond the tube. Then a little Renaissance wax by hand and I'm ready to assemble.
I've tried letting the CA gas off overnight, and then buffing, but didn't see any difference in the results, so don't bother with that anymore.
Typically, prior to CA, I'll sand at most with 400. Depending on the material and the last pass of the skew, I may not sand at all. I just go by feel and visual inspection.
I do sand with 400 and then 600 between about every 3 coats of CA, to a total of about 9 coats. The first several are thin CA and the last several medium CA. I sand with the lathe off up and down the blank, until I can't visually see any marks. I do clean the blank after sanding with alcohol.
To finish it all off, I go wet micro-mesh through 12000, then Novus #2, then Novus #1. All of this is done on the lathe at lowish speed, though I crank it up for the Novus #2 and #1. After that, I sand off the tube ends vertically on a flat piece of 400 to remove any CA that extended beyond the tube. Then a little Renaissance wax by hand and I'm ready to assemble.
I've tried letting the CA gas off overnight, and then buffing, but didn't see any difference in the results, so don't bother with that anymore.
Woodchipper
Member
Thanks,John T. from the another John T. (Woodchipper)
You can buy denatured alcohol or 91% rubbing alcohol (isopropyl alcohol).
You can buy denatured alcohol or 91% rubbing alcohol (isopropyl alcohol).
jttheclockman
Member
Mineral spirits will leave an oil residue, just what you are trying to get rid of. What denatured alcohol did you look at that contained 50% water?? If in a dollar store it probably was medicinal alcohol. I still believe in acetone. Whatever you use be sure to understand the dangers and also protection with gloves.
Skie_M
Member
Dollar store rubbing alcohol comes in 2 grades ... 70% and 91%.
I was using the 91% for a good long while, till I finally picked up some Acetone from Wal-Mart. Acetone has no water content, evaporates just as quickly as 91% isopropyl or faster, still removes oily residue and dust, and is as easy to keep and store as 91% isopropyl (keep away from sparks, flames, sources of ignition, ect ...)
Now ... to answer the OP - "How much sanding is too much???"
There is an obvious answer to how much is too little ... you can see obvious scratches in the wood surface. Some of the more loosely grained woods can be considered pretty much scratch free at around 220 grit, while others will be finely grained woods where 600 grit scratches can be seen with the naked eye.
At this point in time, I sand all my wood blanks up to 1200 grit dry, then wipe with acetone (unless it's a rough finish project, where I still use 91% isopropyl), and then apply BLO + CA for the first coat. I'll add up to 8 - 12 more coats (thin CA from Harbor Freight) before I let it cure overnight, and then I begin the wet-sanding process at 1200 grit and take it up to 12,000 grit, followed by Plast-X and Turtle Wax for the final polish, resulting in a beautiful glassy shine.
Why do I sand it up to 1200? Well, while the naked eye wont discern scratches in the wood, light photons will, and you're magnifying the wood underneath that shiny coat of CA. The remaining oils and the BLO in the finishing process that I use will reflect and refract light in a way that gives rise to chatoyance and other gorgeous effects in the surface of the wood, which is also magnified by the CA layers. I take it to 1200 grit because I think that's where it looks best.
Experiment and see what works best for your finishing needs ... take a sample stock of wood that you have plenty of and make multiple identical blanks, and sand and finish them individually with differing levels of pre-finish sanding but identical finishing techniques, and examine them closely to determine which plan works best for your needs.