Walnut oil and CA

[BCnabe]

Several months ago I started using walnut oil for the last step of sanding to help fill in the grain. I've liked and it does pop the grain nicely.

At about the same time I switched to using Mercury CA (thin and medium flex - M20FT and M300FM) and accelerator.

I've been happy overall with the finish I'm getting but I've had more issues since making this switch with the CA delaminating from the blank near the bushings.

Here's my process: turn the blank; sand up to 400; sand with 400 and walnut oil; let it set for at least 24 hours and then CA.

Typically I will do 4 coats of thin, 4 coats of medium and then 4 coats of thin. I'll also do some light sanding (600 grit) after each stage to keep the finish smooth and to get rid of any ridges that might show up. After that I'll micromesh and buff.

At different stages of applying CA I will snap the bushings off. For years this worked fine but after making the switch I started getting small chips delaminating from the blank - I could see raw wood.

I've tried scoring the blank/bushing joint with a razor blade but that hasn't always helped either. Last night as I was scoring the joint I could see the CA turn white (delaminating) on both the blank and the bushing as I was scoring it. When I took the bushings off the CA was flaking off of the bushing and I had a couple of places on the blank that had bare wood.

I'm wondering if the walnut oil is possibly a culprit - not getting good adhesion between the wood and CA.

This has happened with different species - walnut, leopardwood, osage orange.

I have read that some will wax the bushings but I'm hesitant to do that because I don't want to run the risk of getting wax transferred to the blank.

I'm going to test a couple blanks this weekend from the same piece of wood - one with walnut oil, one with BLO and one without anything but CA.

Has anyone else had any issues similar to this? Anyone else using walnut oil and CA without issue?

 

[jttheclockman]

What you are seeing is fracturing of the CA and breaking the bond on the blank. Just because CA is dry does not mean it is cured. This has been discussed numerous times here. Many people, including myself change to finishing bushings of some sort. Some people just use a live center and dead center and support the blank between these. Some people make special bushings which are just cone shaped bushings from delrin material and support the blank between these and finish. To me this works well. I never use oils with CA. No one here can convince me it does not contaminate the CA and if I am not convinced I do not do it. From old school. 4 coats thin 4 to 5 coats med. Do not sand between coats. I sand between viscosity of CA. Again just my method. Everyone has a method.

 

[magpens]

John, what does this mean, please .... "I sand between viscosity of CA."

As for your questions, BCnabe, like John I do not use any oil, BLO or otherwise, with CA.
As John suggested, I apply CA while holding the blank between conical centers ... steel centers work fine for me as I use only a little bit of CA at a time and the CA never gets to the steel cones. . I probably should make some Delrin cones for holding the blanks.

 

[jttheclockman]

John, what does this mean, please ....

"I sand between viscosity of CA."

As for your questions, BCnabe, like John I do not use any oil, BLO or otherwise, with CA.
As John suggested, I apply CA while holding the blank between conical centers ... steel works fine for me as I use only a little bit of CA at a time and the CA never gets to the steel cones.

Thin CA and Med CA. I will sand if needed to take out any ridges after the Thin CA and then again after the Med CA. Then onto MM. I sand with wet/dry paper 1200 to 2000 then MM.

 

[robertkulp]

I've not used walnut oil with Mercury Flex CA, but BLO works great with it. One of the common problems is applying too heavy of a coat. You need very little Mercury Flex, just 2-3 small drops, per coat. Also, Mercury Flex is designed to have a brief shot of accelerator after each coat. Sanding though, should not be needed between coats. If you need to sand, it sounds like you're applying too much at a time.

I worked with Mercury Adhesives in the development of their Flex CA and these were some of my findings during the early testing. Use very little at a time & you need fewer coats. Use accelerator and don't sand until the very end.

 

[farmer]

Oil

Several months ago I started using walnut oil for the last step of sanding to help fill in the grain. I've liked and it does pop the grain nicely.

At about the same time I switched to using Mercury CA (thin and medium flex - M20FT and M300FM) and accelerator.

I've been happy overall with the finish I'm getting but I've had more issues since making this switch with the CA delaminating from the blank near the bushings.

Here's my process: turn the blank; sand up to 400; sand with 400 and walnut oil; let it set for at least 24 hours and then CA.

Typically I will do 4 coats of thin, 4 coats of medium and then 4 coats of thin. I'll also do some light sanding (600 grit) after each stage to keep the finish smooth and to get rid of any ridges that might show up. After that I'll micromesh and buff.

At different stages of applying CA I will snap the bushings off. For years this worked fine but after making the switch I started getting small chips delaminating from the blank - I could see raw wood.

I've tried scoring the blank/bushing joint with a razor blade but that hasn't always helped either. Last night as I was scoring the joint I could see the CA turn white (delaminating) on both the blank and the bushing as I was scoring it. When I took the bushings off the CA was flaking off of the bushing and I had a couple of places on the blank that had bare wood.

I'm wondering if the walnut oil is possibly a culprit - not getting good adhesion between the wood and CA.

This has happened with different species - walnut, leopardwood, osage orange.

I have read that some will wax the bushings but I'm hesitant to do that because I don't want to run the risk of getting wax transferred to the blank.

I'm going to test a couple blanks this weekend from the same piece of wood - one with walnut oil, one with BLO and one without anything but CA.

Has anyone else had any issues similar to this? Anyone else using walnut oil and CA without issue?

Think about all the wood working books you have read.
You sand with walnut oil ? bet it doesn't suggest that on the bottle
You do your final sanding with the lathe on ? Bet ten bucks that every wood working book in the world says don't sand against or across the grain ..
And your doing it as a final step !
We all sand with the lathe on ...
None of the skilled turners do a final sanding with the lathe on ..
A trained eye can see it .
You always do your final sanding with the lathe off and with the grain ..

Walnut oil and CA is two completely different finishes, not close in comparison .

Wax transferred .
I make my piece long , I don't use mandrels , after I do a finish I trim the ends to length using a live cutter that will not fracture or shatter the end of the wood and finish when getting faced/trimmed to length .

 

[BCnabe]

Think about all the wood working books you have read.
You sand with walnut oil ? bet it doesn't suggest that on the bottle
You do your final sanding with the lathe on ? Bet ten bucks that every wood working book in the world says don't sand against or across the grain ..
And your doing it as a final step !
We all sand with the lathe on ...
None of the skilled turners do a final sanding with the lathe on ..
A trained eye can see it .
You always do your final sanding with the lathe off and with the grain ..

Walnut oil and CA is two completely different finishes, not close in comparison .

Wax transferred .
I make my piece long , I don't use mandrels , after I do a finish I trim the ends to length using a live cutter that will not fracture or shatter the end of the wood and finish when getting faced/trimmed to length .[/quote]


Actually it does say it can be used for sanding on the bottle and on their website: "a few drops of Doctor's Woodshop Walnut Finishing Oil applied to the work as it is sanded will speed up the sanding process significantly. The oil traps the sawdust and forms a sort of rubbing compound that smoothes the wood faster than the sandpaper alone. The oil acts as a lubricant reducing the heat caused by sanding."


By the last step I meant that I use the walnut oil as the last step of turning/sanding before going to the finishing stage of applying CA. I only start applying CA after letting the walnut oil dry for at least 24 hours. Sorry that wasn't clear in my first post.

I'm not sure how sanding with the grain would make a difference in why the CA seems to be delaminating by the bushings. But I do sand lengthwise and after final sanding I will go through several stages of buffing. I'm done when I can't see any scratches radially or lengthwise using a 10x loupe.

 

[BCnabe]

I've not used walnut oil with Mercury Flex CA, but BLO works great with it. One of the common problems is applying too heavy of a coat. You need very little Mercury Flex, just 2-3 small drops, per coat. Also, Mercury Flex is designed to have a brief shot of accelerator after each coat. Sanding though, should not be needed between coats. If you need to sand, it sounds like you're applying too much at a time.

I worked with Mercury Adhesives in the development of their Flex CA and these were some of my findings during the early testing. Use very little at a time & you need fewer coats. Use accelerator and don't sand until the very end.

Thanks Robert - I do like the Mercury CA.

I'm definitely using more than just a couple drops. The sanding I need to do is minimal. I am using accelerator after each application.

If I just use a couple drops per application what do you recommend for filling in the grain such as walnut? That's one of the reasons I started using the walnut oil for sanding because it does a good job of filling in the grain.

 

[robertkulp]

Mercury Flex Thin is great for sealing, but Flex Medium can build up and fill grain. Because it sets more slowly, you don't want to glob it on thickly. Even just a few coats will quickly give a smooth surface for polishing.

 

[GaryMGg]

One other thought: Walnut oil doesn't necessarily cure in 24 hours. Temps, humidity, et al affect the curing time.
I've used Walnut oil during sanding, followed by a CA finish--albeit never tried Mercury--and I burnish the blank after I finish sanding. Heat helps it cure; just don't overheat things.

 

[farmer]

Wood

If you are trying to do a glass like finish using CA then stop loading the water pores in the wood with sawdust and oil and the grit from the sand paper .

When mixing sand paper and oil you get a slurry of grit and sawdust all soaked in oil and jammed packed in the woods water pores .

When you sand against the grain its like trying to pack or load the water pores of the wood with crap that the CA will not be able to fully bond to because its making the CA activate and dry on the crap in the water pores of the wood instead of all of the wood , as in the surface of the wood and down in the water pores to .

 

[Pappi]

I have not used the walnut oil and CA together. I usually use 4 drops of CA thin and 4 drops of CA medium. I sand between the thin and medium coats then i do a final sanding before the MM. These are pens that i have made with the CA method i use.