Why does BLO speed up CA cure time?

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GouletPens

GouletPens

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I'm theorizing without any scientific knowledge on the matter that the driers they use to speed up the curing for BLO also speeds up the CA cure time. I know PURE lindseed oil would take a week or more to cure and the "boiled" part is actually just chemical driers mixed in with the lindseed oil. I just never really thought about why BLO might speed up the curing and wanted to see if this theory makes sense. Am I onto something?:embarrassed:
 
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IIRC , it seemed that BLO actually slowed CA cure time . I could be wrong ! But I gave up BLO/CA finishing , and only use CA now . It will be interesting what others have to say .
 
Does iot really?
Personally, I think it is our imagination that makes it cure faster.

I have been told it was the drying agents, but I suspect that the frictional heat would also contribute. Since the cellulose in the paper and cotton towels we use will accelerate the curing of CA glue, that could have something to do with it.

I use a synthetic applicator, and that seems to extend the curing time.
 
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It is not that blo will cure CA faster, it is used as a lubricant( for lack of a better word) so that the CA can be spread more evenly before it dries too quickly. The heat of rubbing will set the mixture. To me I am still not convinced that by adding blo you are not degrading the CA properties thus making it less hard. Just something does not feel right with that combination. But to each his own as they say. Have a great day.
 
I guess maybe I am just a simple soul... I tried BLO/CA even though I had been using just CA for quite a while... didn't see any difference other than it was harder to apply than plain CA so I went back to using CA plain...

Just never saw any advantage to using BLO... but that is just me I guess :)
 
dalecamino said:
IIRC , it seemed that BLO actually slowed CA cure time . I could be wrong ! But I gave up BLO/CA finishing , and only use CA now . It will be interesting what others have to say .
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Ditto. I had nothing but grief with CA finishing until I quit using BLO. Now it works fine. Medium CA and a spritz of accelerator, repeat until satisfied.
 
This is a message from 2005 in the Yahoo penturner's group. Henk knows much more about the chemistry of glues than I will ever know:

BLO / CA Chemistry
Linseed oil, a (semi-)drying oil, will polymerize under influence of oxygen/radicals. The double bonds in the linseed oil fatty acids 'connect' to each other, and because there are three fatty acids in each molecule, this creates a 3D network of polymer molecules, i.e. a resinous 'plastic'.
BLO, a linseed oil with catalysts added, polymerizes a lot faster, but yields basically the same resin. Since (B)LO is yellow to begin with, the resin also is. Due to light influence over time, LO resin will yellow some more. Can't think of anything that will turn it black, other than fire, sulfuric acid, or maybe a wrong catalyst (or way too much of it).
That being said, the CA/BLO resin is a completely different resin. In BLO, the cross-links occur between individual fatty acid residues, so the triglycerides (the BLO molecules) are attached to one another, creating a true resin. In CA, the cyanoacrylate molecules attach to one another, creating a polyacrylate linear polymer. In CA/BLO, the cyanoacrylate monomers and oligomers (short chains of CA molecules in the process of becoming a polyacrylate) basically act similarly to the catalysts in BLO, in that they accelerate the activation of the fatty acid double bonds. In contrast to the normal BLO reaction though, the CA mono/oligomers actually attach to a fatty acid, then attach another CA or BLO molecule on the other end of their chain. You basically get a resin in which CA mono/oligomers form bridges between the LO molecules, so you get a copolymer resin.
Interestingly, it should be possible to control the average CA chain length in the bridges, thereby influencing the properties of the resin. Whether that can be done by time control, temperature, additives, or choice of CA (thin, thick; methyl, ethyl, octyl, etc), I have no idea. Don't even know whether any research on CA copolymers exists. Haven't found it yet...

Cheers
Henk
====================Heisenberg was right!=========================
| Dr. Henk J.M. Verhaar | |
| Principal | e-mail: hverhaar@environcorp.nl |
| Ecotoxicology specialist | home: henk@stichtsend.xs4all.nl |
| ENVIRON Netherlands B.V. | |
| Zeisteroever 17 | phone: +31 30 698 6218 |
| NL-3704 GB Zeist | fax: +31 30 698 6239 |
| the Netherlands | |
====================Uncertainty happens!==========================


++++++++++++++++
Personally, I find that the medium CA I use hardens much quicker with BLO than plain CA. I do not use CA accelerator due to the potential to cloud the CA if you use to much accelerator.
 
It seems a little funny to me toread about curing CA "Faster". Maybe I am just old but I remember when CA first came out under the name "Instant Glue". In comparison to what was available at that time. CA has no cure time. I have never used BLO for my CA finishes, I am not a chemist, But I do know a thing about things going from liquid to solid etc. Basically to cure Molecules must re arrange, line up and link together. Generally more durable or hard materials take longer to do this, giving more molecules more time to get arragned etc. speeding up the cure time isnot usualy a good thing as you reduce the number of links that get to form. Most things have the cure time they have for a reason. some need ot be heated to get the job done. Heating adds energyto the molecules giving them an added boost to move around. some need longer periods of time because there needs to be a lot of re-arreanging etc. in some cases you can have one solid change to another solid such as in coal to a diamond, this takes lots and lots of time because the enrgy needed is so great to move the molecules. sometimes adding anouther type of molecule will casue the movment to happen faster, slower or even become a different link of molecules. In the case of Epoxy both halves do not have a curing reaction until they are added together. this mixing gives both liquids the molecules they need to start linking up to become a solid.

Now how CA and BLO interact. I do not know specifically, But I also suspect the difference is a slowing down rather than a speeding up. this not only allows the finish to have more linked up molecules, it also allows the CA as a liquid more time to flow and level on it's own.
 
jttheclockman said:
It is not that blo will cure CA faster, it is used as a lubricant( for lack of a better word) so that the CA can be spread more evenly before it dries too quickly. The heat of rubbing will set the mixture. To me I am still not convinced that by adding blo you are not degrading the CA properties thus making it less hard. Just something does not feel right with that combination. But to each his own as they say. Have a great day.
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John, after trying BLO/CA finishes I have found they look good at the start, but they degrade quickly on certain wood, like some Mallee Burls I did, after a few months with out being touched or shown they had nice polished splotches and other areas that looked as though there had been no finish whatsoever put on it, But on some other pens the finish still looks great, I also had the same thing happen on some IBO that was a bit on the punky side.
 
Clearly not everyone is all about some BLO/CA finishes here, myself included. I have been known to put down a thin layer of BLO to pop the grain before applying a straight CA finish to particular burls and woods. Is this not a good practice, or is the amount of BLO not enough to make much of a difference in the durability of the finish?
 
GouletPens said:
Clearly not everyone is all about some BLO/CA finishes here, myself included. I have been known to put down a thin layer of BLO to pop the grain before applying a straight CA finish to particular burls and woods. Is this not a good practice, or is the amount of BLO not enough to make much of a difference in the durability of the finish?
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Brian; For a long time my CA/BLO pens suffered from splotches, but after much experimenting, I determined that the BLO was preventing the CA from adhering to the wood. I modified the application technique so I apply CA first and then BLO. I use a paper towel rolled up into a tube and put a blob of BLO on one spot and three drops of CA separate but near the BLO. I apply the CA FIRST and then shift to the BLO. Other than that, I use the same process used by William Young and demo'd in his video posted on YouTube.

Hope this helps!
 
randyrls said:
Brian; For a long time my CA/BLO pens suffered from splotches, but after much experimenting, I determined that the BLO was preventing the CA from adhering to the wood. I modified the application technique so I apply CA first and then BLO. I use a paper towel rolled up into a tube and put a blob of BLO on one spot and three drops of CA separate but near the BLO. I apply the CA FIRST and then shift to the BLO. Other than that, I use the same process used by William Young and demo'd in his video posted on YouTube.

Hope this helps!
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Randy, I do mine the same way William shows and on most wood it works great, plus it leaves a more natural look, but on a few pens, I've wound up a few months later with areas of shine and areas that were almost bare wood, So far the worst has been on 3 Brown Mallee pens, and they looked great when I put them in my case, and one IBO I had to fix due to a crack in the wood, but it looked like half the finish was missing. I think it has to do with how much oil the wood soaks up on the initial application, I like it for the way BLO pops the grain, also because it's good for wood. I have an Emperor the was oiled let sit 3 or 4 days then sprayed with deft lacquer it loos as good today as it did two years ago. I'm surmising that the more open the grais structure, the more oil it soaks up, I spin mint until it gets beyond warn, same when I start putting the CA on it,. Think of the nasty finishes you get on oily wood with out wiping them down good wit DNA or better with Acetone they may look good right when finished, mos likely not,m but soon after there will be gray or blush areas where the oil was present.,
 
I use BLO?CA finish on all my pens and have not run into any problems. I wash the pen blanks after turned with mineral spirits, then apply a coat of BLO by itself, then after this first coat, I put a couple of drops of BLO with 3 drops of CA on top of it, i put 6 coats on, then a coat of one step polish.
 
That being said, the CA/BLO resin is a completely different resin. In BLO, the cross-links occur between individual fatty acid residues, so the triglycerides (the BLO molecules) are attached to one another, creating a true resin. In CA, the cyanoacrylate molecules attach to one another, creating a polyacrylate linear polymer. In CA/BLO, the cyanoacrylate monomers and oligomers (short chains of CA molecules in the process of becoming a polyacrylate) basically act similarly to the catalysts in BLO, in that they accelerate the activation of the fatty acid double bonds. In contrast to the normal BLO reaction though, the CA mono/oligomers actually attach to a fatty acid, then attach another CA or BLO molecule on the other end of their chain. You basically get a resin in which CA mono/oligomers form bridges between the LO molecules, so you get a copolymer resin.
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:confused::confused::confused:
Science without relating it to the matter at hand. :rolleyes:
That doesn't seem to provide useful information; I know as much now as I knew before I read that.
Can anyone add, in English and lay-persons terms, the pros or cons of what was posted as it relates
to finishing pens using CA versus BLO/CA?!?!?
:biggrin::biggrin:
 
In layman's terms, the BLO and CA do not simply form separate layers on top of each other, they actually bond together to form a single layer.
CA by itself is stable, it needs an activator to set. CA usually relies on humidity in the air to activate it. BLO is another type of activator that will cause the CA to set.
 
bradh said:
In layman's terms, the BLO and CA do not simply form separate layers on top of each other, they actually bond together to form a single layer.
CA by itself is stable, it needs an activator to set. CA usually relies on humidity in the air to activate it. BLO is another type of activator that will cause the CA to set.
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Well then CA should set here as soon as it hits a surface, I've heard that the cellulose in wood and in paper towels helps accelerate the curing of CA. we usually run 50% relative humidity, I think my problems have been more in the quality of the woods than any thing else, Most of my BLO/CA finishes have held up very well.
 
Two things I have found that effected the finish for me isto much blo will cause dull spots to show up right away or shortly after. I put about 1/2 a drop on the paper towel. Just enough to keep the ca from soaking in.

First this I wipe the pen down with alchole or something else to get the oil off then apply a coat of just blo, this prevents any odd color shifts caused the ca and blo not mixing right on the first layer.
 
Whenever I use BLO/CA, I use the BLO to pop the grain then burnish it with cotton cloth or a paper bag to cause it to cure as quickly as possible. Then, I do a regular CA finish over the cured BLO.
 
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