Emery
Member
I'm still new at pen turning but have developed a pretty good method of applying a CA finish. I have seen others use BLO between coats of CA. What is the purpose of the BLO?
if you've got a good CA method down, then BLO is evil. It's useless.
It's for the paeons. Ignore it. Throw it in the trash. Look the other way.
You've got a good thing going.. so DON'T MESS WITH IT!!
But for others, it lubricates.. helps start kick the CA and also helps
the paper towel to not stick to the glue. It works for some, not
so well for others. Whatever works for you is the right way.
Throw it in your NEIGHBOR's trash. I nearly burned the shop down just cleaning up a BLO spill.
I'm still new at pen turning but have developed a pretty good method of applying a CA finish. I have seen others use BLO between coats of CA. What is the purpose of the BLO?
Don:
Henk lost me at crosslinker! I've used BLO a time or two, but I sure ain't no crosslinker
Aren't they the ones who dress funny.)
Andy,
The news is now out. Once you used BLO you are a crosslinker and once a crosslinker always a crosslinker.
Maybe a crosslinker is one who starts a golf game on one course and finishes the game on another one.:biggrin:
Maybe a crosslinker is one who starts a golf game on one course and finishes the game on another one.:biggrin:
Or hits from one fairway, and ends up on the adjacent fairway... been there, done that. :redface:
I'm still new at pen turning but have developed a pretty good method of applying a CA finish. I have seen others use BLO between coats of CA. What is the purpose of the BLO?
Emery,
Your question has been asked several times over. Here is the answer given by a member of another forum.
The answer is from:
Dr. Henk J.M. Verhaar, Principal
ENVIRON Home - ENVIRON Global
Willem Arntszlaan
the Netherlands
Q: Does anyone understand how Boiled Linseed Oil and CA glue react to make such a nice finish?
A: Yes. The CA acts as a crosslinker for the BLO - you basically get an
accellerated linseed oil resin matrix with added durability and water
resistance.
(Normally, oxygen generates radicals in the oil which then act as crosslinkers - a much slower reaction, and resulting in a resin with other properties than a CA-crosslinked BLO resin).
BLO by itself cures through exposure to oxygen. Oxygen from the air will oxidize the double bonds in the fatty acid chains of the BLO triglycerides (and remember, all vegetable oils and animal fats consist of triglycerides). These oxidized triglycerides will then attack further double bonds, and attach to them, so that you get a (3D) network of triglyceride molecules. Basically what you get when BLO cures is a natural resin (plastic if
you like). BLO, in contrast to raw linseed oil, contains catalysts (called a
siccatif, usually consisting of heavy metal salts) that considerably speed up the process. BLO cures in hours to days, whereas raw linseed oil needs weeks to months to cure. However, when combining BLO (or raw linseed oil) with CA, a reaction will take place between the CA and the double bonds of the fatty acids. In effect you get a co-polymer resin of CA
and BLO molecules. Since CA is so reactive, this process is much more rapid than BLO curing. The BLO itself is, ideally, completely 'consumed' by the (excess) CA, so no actual normal BLO curing will take place.
The advantage of CA-BLO over straight CA is that you get a more flexible, less brittle resin than with polymeric CA alone.
I am one of the users of this evil stuff and I really like the finish I get. No, I don't understand the above answer but Henk does know his stuff. I can go with or without boiled linseed oil but I like the finish better using it. So,
my neignhbor is safe. I will keep it in my shop.:biggrin::biggrin:
But, it can be nasty stuff. Do not leave regs soaked with it piled in the shop. It can combust by itself.
I agree that if you have a method that works don't change it.
Do a good turn daily!
Don
I've had people tell me that BLO helps to "pop the grain", whatever that means.
So to figure out what it means, I turned a cherry cylinder, wiped a coat of BLO on half of it, let it dry, then finished the whole thing (I think I used WTF). the BLO portion had a more vivid contrast in the grain. Nothing fantastic, just a noticeable difference.
So, if I have some wood with nice but fairly bland grain, I might put a coat of BLO over it before finishing, but frankly, that's not very often.
HTH
<snip>Maybe a crosslinker is one who starts a golf game on one course and finishes the game on another one.:biggrin:
Do a good turn daily!
Don
I've had people tell me that BLO helps to "pop the grain", whatever that means.
So to figure out what it means, I turned a cherry cylinder, wiped a coat of BLO on half of it, let it dry, then finished the whole thing (I think I used WTF). the BLO portion had a more vivid contrast in the grain. Nothing fantastic, just a noticeable difference.
So, if I have some wood with nice but fairly bland grain, I might put a coat of BLO over it before finishing, but frankly, that's not very often.
HTH
I've had people tell me that BLO helps to "pop the grain", whatever that means.
So to figure out what it means, I turned a cherry cylinder, wiped a coat of BLO on half of it, let it dry, then finished the whole thing (I think I used WTF).
...
Update:
As expected, woodturners finish did not do well over BLO. It was going on great, went through the micromesh beautifully, but when I polished with the mequiars, it lifted right off. I am next going to test letting the BLO cure for a week, and try again. There are just so many woods (burls and juniper are prime examples) that look so much better after popping the grain with BLO before a finish, but I still want a durable finish on top.
Since Woodturner's Finish is water-based you will most likely to continue to have problems. There is even a good chance that if you get Woodturner's Finish to stick to BLO you'll see problems a few years down the road.
What might be worth trying is to add a coat of dewaxed shellac over the BLO before you apply Woodturner's Finish.
Good Luck
I've had people tell me that BLO helps to "pop the grain", whatever that means.
HTH
"Pop the grain" means getting the grain to be more pronounced. BLO does this through a colour change; you can also get the same effect by sanding ulta-smooth before CA. Read about this on Russ Fairfield's site (at the bottom of the page):
FS-5