Thread: Sanding blanks

Some timbers, no matter how much you sand, have little divots etc. That is why my CA technique starts with thin, but finishes with thick, so fills any imperfections.

I have only just started using the thick CA when I was running low on the thin. I put 2 coats of thin on and then 16 coats of thick. On some blanks the white powder from the CA began to show up towards the last coat and after applying the accelerator. So I put another 2 coats of thin over it and it dissolved the powder and left the shiny finish. I might have been applying the thick CA too heavily.

I find to eliminate those dimples completely, you need to let the finish cure overnight before you do your final sand and pollish. Those small pockets of CA take longer to fully cure, the CA seems to shrink when cured, so the dimples will come back otherwise.

Since I have started doing this my overall finish has improved greatly.

i never use anything but thin, i've never had sucsess with the others, i dont sand between, each layer is too thin to i rekon, or during, i do sand to 800 prior though, its the buildup of the ca that i want to flatten out and polish up.

Neal.

Originally Posted by plantagenon

A question or two:

After turning blanks, sanding to 600, applyinig a coat of CA and sanding with MM, very small dips appear in the timber which are shown up by CA lustre with the rest of the blank being dull. It is a sanding problem.

I am not sure this is a sanding problem. Open grained woods, like red oak, will always show this problem.
I use a method called: wet sanding with CA. You start with a fairly course bit of sandpaper, usually 220 to 320 range, put a small parts bag behind it so you don't get glued to your blank (don't ask how I know this please). With the lathe running, start sanding and allow some sanding dust to build up on the sandpaper. Keep the paper moving to avoid deep scratch marks. After about 15 seconds you should have enough dust. Drip medium CA on the top of the blank while you continue to hold the sandpaper under the blank. Move the sandpaper around to get the CA and sawdust mix to spead over all the wood. Stop the lathe and let the CA flow out and set.
Let the blank sit for an hour then sand, finish, sand and buff normally. The wet sanding step fills the open grain better than many layers of just CA.
You might have to substitute thin or thick CA depending on your local humidity conditions. Medium CA works best for me here in Southern Ontario, Canada.

Hope this helps,
Brad
HardingPens.ca

That seems like a complex process Brad. I gather the small parts bag is a small plastic bag held behind the sandpaper? I can't see how that is going to help stop the sandpaper sticking to the blank. However, I might be missing the point. I can see what you are describing by gluing sawdust back into the blank with the CA. Does it distribute evenly over the blank once the CA hits it?

Thanks

yeh i can see where he's gone with that Greg. Because the CA / sanding mix is sliding past the paper, its not to stop the paper from sticking to the work, it's to stop you yourself from being glued to the paper and then the blank, or the paper to your fingers after you got it off the blank as the paper would absorb the wet mix.

i think it'd have a similar effect of not blowing off the blank with compressed air after sanding normal grits dry, pre CA. Might be something to try on more open grained wood, i'll have a crack at it.

Neal.

Let me know how it goes but I have a few doubts although it would probably distribute the dust better then just putting it on a bit of paper and running it along with CA. It would fill the gaps on open grained timber as you said, but that is not the problem I am having. I managed to overcome it today using thin CA to start with and then thick CA to fill the dips, however, my thick CA was not as fluid as it has been and built up a wave on the blank so it was back to sanding to cut if off and then back to thin CA to finish it off.

With my limited experience with wood pens i think ironwood has the right of it, from memory, depends a lot on the wood and its moisture level, and its "working life movement", so the pores are sucking in the ca a little and the deeper pockets are shrinking, try as IW said, do your thing as normal but try only doing like 3 coats of thin (to let em get into the pores and seal it up) and leave it overnight, then do your other coats and final sand / polishes the next day. Perhaps even MM'ing the 3 coats carefully prior to the rest on the second day. Thats what i'd try.

Neal.

Originally Posted by thompy

yeh i can see where he's gone with that Greg. Because the CA / sanding mix is sliding past the paper, its not to stop the paper from sticking to the work, it's to stop you yourself from being glued to the paper and then the blank, or the paper to your fingers after you got it off the blank as the paper would absorb the wet mix.
......
Neal.

You are correct, the CA will seep thru the paper, onto your finger and you will become one with the paper.

The blank will be quite rough after this process and it will need a good sanding, but after you sand it, the pores will be filled with the CA sawdust mix. I start sanding with 150 along the grain only, then 220 with the grain and with the lathe on and progress thru all the grits.
This is the quickest way I know to a level the blank surface on open grained woods.

Brad

With the CA sticking, I use disposable gloves we can buy here in the supermarket for around $8 for 100. That stops the CA sticking and also protects your skin from absorbing dangerous chemicals. I use them whenever I am gluing or applying CA or Minwax or Nitro dipping.