I just finished 3 one inch test wraps of black nylon(different mfgrs) on a black blank. Gudebrod and 2 others of which I won't mention as one is pure Cxxp. I made sure the wraps were packed tight and applied
Flex coat to the threads using no CP. When cured I took a jewelers eyepiece and noticed individual threads intermittently had lost the black dye and the natural nylon color was showing through. This sequence appeared on all 3 wraps with Gudebrod being the least.
I hesitate to blame Flex Coat as there must be some explanation as to why this happens. I am aware that most suggest no CP on black nylon but something is allowing the dye to be stripped off of the thread.
By the way I applied the finish on an 18 rpm motor.
I mean no disrespect but I would leave this to the most experienced on this site for an explanation.
Thanks,
Joe

Joe,
Actually, I have never heard of this issue before.
I suppose that it might be possible that the color could be lost if there was a great deal of packing done with a packing tool.

Just as another test, do another test wrap, without use of any packing tool before you do the finish test.

I generally use a packing tool very little. I just keep a very tight tension on the thread, and use about a 10 to 15 degree offset on the incoming thread and there is generally no need for additional packing. If I do any packing, I use the edge of my plastic packing tool.

What is the particular tool that you use for packing?

I suppose that you could do another test where you take each of your thread types and lay the thread out on a hard surface and go after the thread in the same way as you do, when you pack the thread. Then, look at the thread under the magnifier and see what the thread looks like before and after packing.

Let us know what you find.

p.s.
This is the style "burnishing and packing" tool that I currently use for my thread packing and burnishing.
[www.mudhole.com]

Good luck

I'm wondering how much magnification you are using ? As stated make a few more wraps and inspect before applying finish. Is the condition visible to the naked eye ? I go over decorative wraps looking for gaps with 2.0 reading glasses and I find some I would most likely never see otherwise. Just wondering if the magnification is discovering a problem that is really irrelevant.

Freddwhy (Rapt-Ryte)

Answer to your questions-1 the wraps were not burnished the packing was done from the edges just pushing the wraps together Nothing touched the main body of the wrap.
2-the condition is visible to the naked eye in the light- the eyepiece allows for extremely clear picture of the individual threads. The Flex Coat is dead clear so it wasn't a mix problem.
If the threads were running longitudinally they would appear to be tiny hairline cracks. I assure you this is not the case!

Joe, have you done a test wraps without the epoxy, and used the eyepiece to look at it? Also, what size thread are you using?

If it looks good out side in the sun without the glass --- it's done

Bill - willierods.com

I wrapped some just now without epoxy and the threads are black using the eyepiece . In answer to Bill -It's not done-out in the sun it can be seen clearly through the finish

I have never seen this with any black thread I guess this is Regular nylon thread Not NCP thread It will have a different color

Bill - willierods.com

I'm not sure you have a dye issue, it may be an optical issue, reflections or something. Three different brands of thread, long proven epoxy, apparently never experienced before, makes me really suspicious it is not as it may appear.

Is it possible to remove the wrap and inspect the thread? I sure would like to see a picture . With my iPhone I can edit a photo and zoom way in.

Freddwhy (Rapt-Ryte)

The Flex Coat you used, did you "thin" it with anything or apply it straight up?

Reason I ask is that I saw a similar problem once where a builder used a Solvent to thin the finish.

Joe,If you don't think it was the Flex-Coat then it had to be something on your hands. Flex-Coat is not a bad product but,(in me own experiance) is the only one I ever had an issue with blushing and flash set up after mixing with the correct 50/50 mix. I don't think Flex-Coat had anything to do with it eather, are you sure that's not air trapped or imbedded in the thread fibers.Did you use any sort of heat to disperse the air or moisture from within the mix?

Dennis J. Danku
(Sayreville,NJ)

if you have another spool of blank try a tst wrap See if it happens again
I use flexcoat UV and thin it have not seen anything on black

Bill - willierods.com

I'm back,
I did my last test. I've had it. However I am leaning towards it being a thread tension problem. I used the same blk. nylon ,this time with CP and without CP-same flex coat lite build. The lines appeared just as before.
This time I varied the tension on the threads from light to extremely tight. My best example of the lines showing up is that if you took a solid white blank and painted it with black paint and after it dried you took a pin and made a series of scratches in the black paint while the rod was rotating , you wind up with whitish marks along the blank
.
On this last test some areas were fine(solid black) and other areas had the lines, some singular and some multiple that could be seen through the finish.
I can't think of anything else it could be. Thread was good. finish was good. dry temp good, rotation at 18 rpms.

Well that's it ,
Joe

Pictures would certainly help

Freddwhy (Rapt-Ryte)

Joe,
What are you using for a thread tension device?
Do you think that you are changing the thread from the thread tension device?

I use the simple spring loaded pair of disks to apply tension on the thread as I wrap. I have personally never experienced the issue that you are having.

If you suspect that it could be the tension device, use a tension device that puts tension on the thread spool, rather than the thread.

Also, just as a double check, if you do use the disk / spring tension device, disassemble the tension device and check the face of each disk for burrs or anything that might damage the thread. If in doubt, polish the disks, using polishing compound and a polishing wheel, or similar device.

Good luck

You can also try wrapping a piece of scrap blank Not using the tensioner put put some tension on the thread with ( clean ) finger pressure Then see how it looks
As said tension on the spool keeps the thread cleaner

Bill - willierods.com

Finally solved the problem!
I took a piece of 1"smooth charcoal blank. I figured the result would be more pronounced. I wrapped 2 inches of black nylon A and varied the thread tension from light to real tight and put a coat of CP on it.
The thread produced gaps that you could not see unless you had a strong magnifier. I applied FC finish epoxy and let it cure.
As I suspected the lines showed up! The lines were less wide than the A thread itself and were whitish to slightly yellowish looking. It turned out that that the lines produced is epoxy in the gaps and depending on the lighting can be seen more or less. Not all of the wrap was affected, only where there were gaps that could not be seen with the eye.
What I took from this is:
make sure tension is constant and not too tight
make sure the wraps are packed and burnished properly done under strong lighting
and IMPORTANT!- Don't ever use CP on black nylon unless you want greyish looking wraps.

Thanks to all for trying to help ,
Joe



Edited 1 time(s). Last edit at 03/12/2015 12:18PM by joe ponzio.