Painting tubes vs blanks

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leehljp

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Tunica, Mississippi,
That was a great link and great visual aid!

There was another link (which I thought I had) about the color of paint, and how the "color" of paint affects the outcome of cast blanks.
Found it: http://www.penturners.org/forum/f19/seeing-believing-reverse-painting-151785/

In the video you linked - He did refer to "discoloration" in the "painting the tube only" after gluing with both CA and Epoxy. That "discoloration" is not actually discoloration but rather shows very clearly where glue is NOT adhering to both the tube and the blank. This is Very Important to understand. It is this point that is one of the causes of blowouts in wood and sometimes cast blanks. The "discoloration" is where there is NO adhesion. It is adhering enough to prevent him from twisting or pushing the tubes out, but the force of 1000, 2000 or 3000 RPM and the cutting of the chisel on blanks that are barely glued in - is what causes blowouts in so many cases.

The "discoloration" is actually the clear blank being foggy/unsmooth/rough from drilling. Take a clear blank, drill it to where you see the rough inside, and coat the inside with CA, epoxy, clear oil or water and suddenly it will show clear.

On his "Tube Only" it was the small area of contact points of the glue that were clear. Notice how fractional that area is. This is what happens in most gluing situations, and why some people swear by polyurethane glues - the glue expands and makes contact in almost all areas between the tube and blank where as CA and epoxy does not. The disadvantage to poly glues are that the tubes must be taped in, or the expanding glue will sometimes push the tube out as it hardens.
 
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RogerC

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Jan 30, 2017
Messages
149
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Oklahoma
Nice video from Lynn Lacey this morning comparing techniques.
https://youtu.be/Lb7XYWkc48M

That was a great link and great visual aid!

There was another link (which I thought I had) about the color of paint, and how the "color" of paint affects the outcome of cast blanks.
Found it: http://www.penturners.org/forum/f19/seeing-believing-reverse-painting-151785/

In the video you linked - He did refer to "discoloration" in the "painting the tube only" after gluing with both CA and Epoxy. That "discoloration" is not actually discoloration but rather shows very clearly where glue is NOT adhering to both the tube and the blank. This is Very Important to understand. It is this point that is one of the causes of blowouts in wood and sometimes cast blanks. The "discoloration" is where there is NO adhesion. It is adhering enough to prevent him from twisting or pushing the tubes out, but the force of 1000, 2000 or 3000 RPM and the cutting of the chisel on blanks that are barely glued in - is what causes blowouts in so many cases.

The "discoloration" is actually the clear blank being foggy/unsmooth/rough from drilling. Take a clear blank, drill it to where you see the rough inside, and coat the inside with CA, epoxy, clear oil or water and suddenly it will show clear.

On his "Tube Only" it was the small area of contact points of the glue that were clear. Notice how fractional that area is. This is what happens in most gluing situations, and why some people swear by polyurethane glues - the glue expands and makes contact in almost all areas between the tube and blank where as CA and epoxy does not. The disadvantage to poly glues are that the tubes must be taped in, or the expanding glue will sometimes push the tube out as it hardens.
Thanks for both of those links, gentlemen! As someone who still has much to learn and has yet to turn acrylics, these go a long way on educating me.
 

cjester

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Nov 26, 2015
Messages
157
Location
Illinois
That was a great link and great visual aid!

There was another link (which I thought I had) about the color of paint, and how the "color" of paint affects the outcome of cast blanks.

It is amazing how much of a difference that can make. We saw some other examples at a Chicago chapter meeting, with equally dramatic differences in the end result.

In the video you linked - He did refer to "discoloration" in the "painting the tube only" after gluing with both CA and Epoxy.

Good points on the gluing. I understood what I was looking at when he got to that point, but it's a good reminder to be careful and thorough with gluing, regardless of adhesive. When gluing in with epoxy, it's easy to assume that it's thick enough to provide complete adhesion automatically. Clearly (pun intended) not true!
 

crokett

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Dec 4, 2012
Messages
610
Location
Mebane, North Carolina
I paint only the blanks. I use acrylic paint, it seems to work just fine. I also don't use CA for gluing tubes. I only use epoxy, and I use acid brushes for mixing and spreading on the tube. The acid brushes ensure better coverage than popsicle sticks. I spread it to about 75% the length of the tube, then insert the tube to the glue line, then spread the squeeze out on the rest of the tube then push the tube in the rest of the way. I quit getting blowouts when I switched to epoxy and started using this method. I pay special attention to the ends of the blank, this is where all of my blowouts have happened.
 
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