jtruesdell29
Hi,

I've been working on dyeing SLS printed nylon parts with black iDye Poly. When I add the dye to boiling water, a shiny, brown film forms on the surface that sticks to the parts and causes an uneven finish. Is there any way to prevent this? I've tried washing afterwards with hot water and detergent but I cannot seem to get it off after the fact either.

Thanks,

Jeremiah
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Jacquardmod Jacquardmod
I have hear this before. I am not sure what this is.  Is it a part of the softening of the nylon for printing?  Can it be soaked up?  Does it come from the dye intensifier?  Are you using dye intensifier?  It is probably hydrophobic because it floats.  I have heard of people solving things like that by putting a bunch of cut hair in a porous bag and running it over the surface.  It pulls the oily stuff out of the bath.  
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jtruesdell29
Thanks for the suggestion. I did use the color intensifier since I'm looking for a really deep black, which is hard to achieve. I've tried soaking it up with paper towels, but it doesn't seem to help much. It sticks to the surface of the parts almost instantly. I don't think it's from the parts themselves, but it is possible since the powder I'm using is already pigmented with a grey color. I do soak the parts beforehand in boiling water and I don't see it forming on the surface during that step. 
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BinDW
I too have this oily problem but only with black. I have tried using the intensifier and without and the oily scum appears either way. I have used red, crimson, blue and orange without the oily residue. This has led to me thinking it related to the formulation of the black dye. 
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jtruesdell29
BinDW wrote:
I too have this oily problem but only with black. I have tried using the intensifier and without and the oily scum appears either way. I have used red, crimson, blue and orange without the oily residue. This has led to me thinking it related to the formulation of the black dye. 


Thanks for the input. I'll try picking it up with some polyfill in a mesh bag instead of paper towels.

Its disappointing because aside from this problem, this dye makes a way darker and more consistent black color than any other dye I've tried.
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Jacquardmod Jacquardmod
That is interesting intel from BinDW.  I had not heard that the black was unique to this situation.  Some dyes are sprayed with an oil to prevent them from being airborne and getting kicked up into the air.  I wonder if this is what you are seeing or if it is something else?  We do not need it with this dye since it is in the dissolvable pack.  Let me check to see if we can get more information on this.  

Are either of you dissolving the whole package?  I realize it isn't happening with the other colors, but I want to make sure there is no easy fix like cutting open that package instead of dissolving it.  

Let me investigate this further.  
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Jacquardmod Jacquardmod
@jtruesdell29 Can you let us know if skimming with the polyfill works?  Also, if either of you can post pictures, that would be helpful.
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jtruesdell29
I have not been using the packet. Since I’m doing small volumes of dye I cut the packet open and measure out an amount of powder. I’ll post pictures next time I use it.
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BinDW
I just drop the whole dissolvable packet into a pan of  boiling water.
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BinDW
I have never cut the packet open with any of the colours.
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Jacquardmod Jacquardmod
I got word from our supplier and they do not add anything to the powder, which makes it seem like it is an inherent quality to the dye itself.  Are your 3d parts the standard white nylon? If so I have some of those and i might send them to our supplier to see if anything can be done.  Sounds like this "oil" is a byproduct of the manufacturing process for black.  
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jtruesdell29
It's grey nylon, but otherwise standard PA12 powder. 
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jtruesdell29
Here's a picture of the film on a dyed part. On the left is a part with a lot of the shiny film. In the middle is a part without the film. Both were dyed with iDye Poly black. On the right is a part straight from the printer.
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Jacquardmod Jacquardmod
So it makes it sort of brown and resists dyeing in those areas.  That is so odd.  Interesting
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jtruesdell29


I got word from our supplier and they do not add anything to the powder, which makes it seem like it is an inherent quality to the dye itself.  Are your 3d parts the standard white nylon? If so I have some of those and i might send them to our supplier to see if anything can be done.  Sounds like this "oil" is a byproduct of the manufacturing process for black.  


Are there any additives or emulsifiers you can think of that might help this stuff stay in solution rather than float to the top?
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