Black dye WSF & PWSF

Mitchell at Shapeways went the extra mile and got us a credit to use to make some parts for dye testing. We've submitted the parts, which are primarily small pieces which are 1/2 polished, the other half unpolished, to Shapeways for fabrication. They've been printed & are in transit to us. When we get them we'll send to Jacquard for testing - should be sometime week.
We'll post the results as soon as we get them.

I really appreciate the efforts and tests for black dying. a polished black dye would be great. (also a grey would be fantastic)

We shipped off the samples to Jacquard to be test dyed. There are both polished and unpolished samples they will test.
We had equally good results with both polished and unpolished - the black polished had a quite nice look and feel.

Hopefully Monty at Jacquard will be able to replicate the results and/or find a better approach that can be consistently used by all.
I'll let everyone know what the results are.

this is all very interesting testing happening here.

I am looking at selling many SLS parts into production manufacturing facilities for end us (to replace small lot runs of injection molded parts). What I have been requested by customers is that the white SLS parts get extremely dirty and greasy very fast... the mechanics handle these parts with dirty/greasy hands and the nylon just soaks it all up like a sponge. It is then very difficult to get the dirt/grease out.

So my customer has requested if the parts can come in a darker color to hide the dirt/grease. Instead of using a 'black sls powder' to begin with, I figure dyeing the parts would be the most cost effective means of achieving this.

A big concern of mine however are the following..

1.) the customers often autoclave the parts at 250 degrees for 30-60 minutes. The SLS nylon does soften up but it does not render the part unusable. Once the part cools it still seems to be very close dimensionally as it was before autoclaving. This sure beats the heck out of the prior method of making parts from extremely expensive PEEK material in order to be autoclaved. But will the dye 'bleed out' if autoclaved?

2.) customers also put the parts through their wash rooms under very hot water (I would guess close to boiling temps), sometimes submerging the parts for an hour to clean them of all dirt/grease, etc. My concerns are that if I give them dyed parts, will the dye 'bleed out' when submerged into boiling water?

If the dye is permanent and there is no way it bleeds out, then this would be an awesome outcome! sure would beat painting the parts, as painting is the last thing I want to do.

Im assuming you're talking degrees F. From what little experience i have with boiling the parts in dye, the dye seems to be permanent.
Once it dries completely it doesn't tend to come off unless exposed to some solvents.

I just talked with Monty and got a pix of the results from his dye tests. Couple of interesting points:
- acid dye did not work at all - he said he had never seen a material which repelled the dye as thoroughly
- he went with a much stronger concentration of iPoly dye than we used, and got a jet black result (see pix) Black is the most difficult "color" to achieve for ANY dying process.

So what he recommended was using 8-10% (he used 8%) by weight of iPoly dye and carrier, and running at a rolling boil (100C) for 30m. Running at a boil would prevent the gunk buildup issue we saw, and should allow for simple easy cleanup of the part in post dye rinsing. Use equal parts dye and carrier (or intensifier) in the mix.
By my math, this is 10X the concentration we were using! We used 8 cups of water, which is about 2 kilos. One packet is 14ml of dye, 14g carrier or about 0.7%.
He recommended we buy direct from them, and talk to Victoria Garcia to order the dye and carrier in bulk - buying the packets will be much more expensive otherwise.
Maybe a lower concentration would work, but we'll run some tests using this formula and see how well it works on our regular parts.
I would imagine with this strong concentration, one could dye quite a few parts before needing to change the bath.

Thanks for the update.

Do you mean 8-10% of dye per water, or per polymide?

I spoke to Monty a while ago and he told me to use 8-10% per weight of polymide, so with a 100g piece of 3D printed part, to use 10g of dye, or just dump the whole 14g pack in with it.

If you mean by concentration of water, then it would be hard to judge, like using 1.4kg of water with a 14g packet of dye for 10%, but what happens if you dye maybe 3x of 100g of polymide, instead of just 1 piece, and what happens if reusing the bath for multiple boils?

THanks
THomas

You are correct, I talked with Monty again and got the correction
I misunderstood - it should be 8% of dye relative to the weight of the parts you are dying, nothing to do with water volume.
SO for example with our parts which are about 34g each, in our original bath we were running 3 parts or about 100g with one packet of dye, 14g, or 14%.

My impression after talking with Monty is the trick was very high dye concentration - but it seems that's what we've been using already.
My impression was the WSF dyed black more readily than the PWSF.
He tested the WSF, but not the PWSF yet. He is going to run that this afternoon - may know more then.

I spoke with Monty again - he tried the same dye formula on the PWSF parts, and he could not tell any difference. Both were jet black.
We are going to be running some black parts in the next few days - I'll post the results after I try them with the boiling mode.

It would be interesting to know whether boiling/dying the PA affects the surface.

I'm curious to know whether another round of polishing, or another sand blasting would help the surface finish after boiling/dying.

Has anybody determined if the soaking in dye changes the shape/size of the parts? if you say are trying to hold a critical I.D. measurement of 1", after SLS the I.D. measures exactly 1". After soaking in hot water and dyeing, will the I.D. still measure exactly 1" or does it change by .005 - .010" ?

We haven't tried any exact measurements, but our cases do require that the size doesn't change more than 50-100u, or we would see it in how tight the phones fit in the cases. We haven't seen any such change in the dimensions.

I've attempted to dye some of my parts with the iPoly dye from Jacquard.
They look fantastic, but unfortunately, the amount of cleaning/scrubbing/soaking AFTER
the dyeing process is daunting if one wanted to do this on a large amount of parts...

without the cleaning/scrubbing/soaking, the dye tends to bleed onto lighter colored parts,
and onto ones fingers.

any advice?

The buildup of dye on the parts seems to be from the low temperature processing, and the long dye times. You may be able to minimize this with higher temperatures and shorter dye times.
We use a sponge, wear disposable gloves, and wipe the excess material off while running under warm water.
We then let the unit dry for at least one day - this tends to minimize bleed.

the iDye poly rubs off too much. My hands get stained. I'm clear coating to add scratch protection and sealing in the pigments, but this would not work for low cost, high quantity parts.

I have tried acid dye before, but this was more than 6 months ago and i cant remember the results. I thought I got a better result though but you'll have to try it yourself to confirm.

I've had to go up to 1 hour of boiling with idye and acid to get them to stick though. To clean off the excess powder, you should wash them again at 60-80C with a bit of detergent or vinegar. But it won't fix the problem, just reduces the amount of staining.

I've also purchased an ultrasonic cleaner to try and get rid of as much loose powder from the parts before dying. It seems to get most of the powder off but not all. They work best with cleaning metal parts, but plastic is a bit different. I got one of those stainless steel rectangular units with a 120W power output. They're a bit more expensive than the small ones you find in electronic stores for cleaning eyeglasses and jewelry, and twice as expensive. My unit also comes with a heater, so it should be useful for the post-washing too.

I'll be experimenting with something called polymethcolours soon, manufactured by a company in Germany called Büfa. But I think they sell in large quantities to companies only. Their brochure claims to take only 15-20 minutes to work. The actual pigments don't work on their own. They require a catalyst to be added together with the pigments. The brochure also instructs to stay below 96C, because bubbles from the gassing water interferes with the bonding of the pigments to the parts.

I'll post some results in a week or so.

What did you use for the clear coat?

I used a 2 component automotive clear coat. I think its a polish brand or somewhere from eastern europe called Profix CM 10 Matt, 2 to 1 mix with thinner. It makes a really hard coat, but it is a lot of labor, which is why I'm not sure it's good for large quantities of small parts.

One problem I'm having with the clear coat is that I'm trying to tumble my own polished parts, but I don't have the right media. The results I have is a fuzzy uniform surface, which looks nice when it's white, but when dyed, the ceramic powder from the media creates quite a lot of staining. So I may just resort to having the 3D print companies to polish the parts.

But if the surface is fuzzy and not smooth, the clear coat will harden the fuzzy fiber into a really bumpy ugly surface.

So the clear coat is appropriate only on hard surfaces. I've tried it on the default sandblasted surface and it's pretty good. I like the matt better than glossy because it doesn't highlight all the pores of the 3D printed parts. I'll be getting polished parts soon, so I can finally get on with further testing.

My plans for the next step is to test this polymethcolour, and if it works well without staining, I'll use this on pre-polished parts. For small parts, I won't use the clear coat. For larger parts that are part of a more expensive assembly, I will clear coat.

I tested this Buefa dispersion dye. It is not black, it's more like purple, but I did this at 96-99C as directed. I'll try this again at 100-105 C later.
I used their Lavegal for pre and post wash, and it does not stain at all.

The rings on the left are normal sandblasted while the main part at the bottom is polished. The polished part came out dyed much lighter, and the grinding pock marks are very visible. I'm not sure the polished surface looks so good when it's dark. It looks really nice when white, and also feels very well. But it looks to me like the normal sand blast surface looks better when dark.

I wonder if this Lavegal wash would work with iDye Poly or Lanaset dye to prevent staining. It could be similar to Synthrapol. iDye Poly is also a dispersion dye, just like the Buefa Polymeth that I tested today, but iDye Poly recommends roiling boil while Buefa says not to reach boil.

I accidentally left a part in the dye bath for 3 hours off the stove, while cooling down back to room temp, and the part actually came out more black.

I wonder if the secret is to go from 80 to boil for 30min to 1 hour, then let it sit and cool down for maybe 1 hour.

But this was an unpolished part, just the standard sandblast, which looks much better when dyed black than a polished part.

I did another test and boiled it and it came out darker. However, my digital thermometer keeps fluctuating and may not be accurate. When I did my 1st test I kept it a reading of 96. When I boiled, the thermometer said 125 C which doesn't sound right. Can there be so much salt in the solution that the boiling temperature goes up so high?

Perhaps my first test was not so good because my thermometer is not working and I was maybe somewhere at 80C.

Also, for my post wash I am using the Lavegal from Buefa, with an ultrasonic cleaner. Without the ultrasonic cleaner, the cleaning bath actually stays quite clear, but with the ultrasonic bubbles, the excess dye immediately goes into the bath and it turns purple. But I wonder if it is also removing dye and making the color less dark?

After post wash, there is no staining of the hands.

I want to try this test again with acid dye and iDye poly, but I ran out and need to get more. I will try it with the method of going from 80C to boil and then down to room temp, then cleaning with the ultrasonic cleaner to get rid of excess dye to prevent staining.

I found out that the cool down only makes the parts darker because the dye powder tends to cake to the part as it cools down. After post wash, that excess dye gets washed out and the color dulls back to it's pre cool down color.

However, boiling did make the color darker than non-boiling, but I have no idea what temperature I was using before as my thermometer is most likely cheap and broken.

The Buefa dye didn't make a good black, it's more blue. The blue is acceptably dark on non-polished parts, but not good enough on polished. But it doesn't stain after post washing with it's proprietary liquids.

Polished surface actually looks more like plywood chip board. It doesn't look pretty at all when dark. When it's white or light, it's not noticeable. The only way I think to hide the polished surface when dyed black is to clear coat it. When the surface if filled in or coated, the reflected light becomes more uniform instead of the "chipboard".

I'm going to try the acid and idye again. Anybody used the iDye natural, or only the Poly?

I may try the Lanaset again also, but they are really expensive, almost 2-4 times more than the Jacquard dyes, and I'm not sure where to find quantities of 1-5 LB to be shipped internationally.

Anybody asked i.competitive service what black dye they use? Their black is true black. They also don't give a discount on volume for dyeing, so it comes out very expensive.