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 Post subject: Using 15psi Pressure Cooker with Black Rit Dye to color SW&F
PostPosted: Sun Oct 20, 2013 11:24 am 
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Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
I've just dyed my first parts with a 15psi Pressure Cooker and I made some interesting observations. Yes, I know this thread would probably be better with pictures but I'm having camera issues at the moment and I doubt my cell phone would capture the detail needed.

Always here is the mix I used:

3 gallons of tap water
1/3 cup of non-iodized salt
1 teaspoon of Calsolene Oil
1 TBS of Citric Acid Powder
1 cup of white distilled vinegar
2 packages of black Rit Dye

The cook time at 15psi was about 1.5 hours and in this time the fluid level dropped from about 6 to 5 inches. The parts were contained in a mesh cage to keep them submerged.

The initial results were very poor. The parts came out a very dark ugly green color. I also noticed that I could see the cage at the bottom of the pressure cooker through several inches of water so it appeared there was very little dye left in solution at this point. So what I did was add 4 more packages of black Rit Dye (to make for 6 total) without adding anything else. I then re-dyed everything for over 3 hours at 15psi and I let the pressure cooker cool over night before opening it this morning. There was about 2 inches of fluid remaining as the top of the cage was just sticking out but the water was a nice opaque black as you couldn't see past the surface. The parts are a very nice rich black but I'm not sure if they are any blacker then they would be had I simply boiled them as I have in the past.

The Negatives:
(1) It appears you need ALOT more Rit Dye to get the same rich black. In the past I've obtained a nice rich black with simple boiling and a single bag of Rit Dye.
(2) The cost of a pressure cooker.
(3) There is no easy way to monitor the fluid level during the process. You certainly don't want to run things dry. I'm wondering if I should set the hot plate/pressure cooker on top of a scale as I think that would allow for a way to monitor fluid level. Though this test tells me if one assumes a drop of about an inch per hour they are probably safe.

The Positives:
(1) There is minimal to almost no bleeding of the black after dying. I could rinse the parts in water and the water stayed clear. With simple boiling I can rinse the parts dozens of times and they continue to turn the water black. I'm hoping this is a good sign as with my gear cube kit I glue colored SW&F tiles onto these black parts and with my first puzzle my attempts to seal the puzzle resulted in some black bleeding into the colors parts. So I think this is a very good sign.

The black may go deeper into the parts with pressure cooking but without cutting the parts I can't tell. To me it appears the higher temperature obtained with pressure cooking actually breaks down the dye while its still in solution. I was thinking I'd read this observation by someone else before and I did a search of Brandon's post as I thought it was something he had said but I couldn't find it. Even the 2 inches of solution that was nice and opaque didn't seem to have the staining power that the solution left after boiling had. You invariably get a few drops on your hands or a table surface and it wipes up without making a permanent black spot. What you get on your hands washes off with a little soap and water. So in some sense this made clean up a little easier. Still I used a hot plate and did this in my garage... I would NOT recommend you do this in your wife's kitchen. LOL!!!

I know Brandon uses a pressure cooker, not sure anyone else does but I'd be curious if my observations were comparable to others that have tried this. I'm now also curious if its possible to buy Black Rit dye power in something other then those 1-1/8 oz boxes. If I stick with this method it seems I may want to buy the stuff by the gallon.

Carl

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 Post subject: Re: Using 15psi Pressure Cooker with Black Rit Dye to color
PostPosted: Sun Oct 20, 2013 11:37 am 
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Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
Hey Carl, a few comments:

I haven't dyed a small amount of parts in my pressure cooker. Every time I've used it there were tons of parts. For example I dyed all 8 Bubbloid122 prints at the same time. Because of the number of parts I've been dying with it, I've been using 4 Rit dye packs at a time.

Regarding the drop in water level, I have not had the same problem. Once I get the cooker up to pressure and the regulator weight is hopping up in down from escaping steam I've turned the stove down to the point where the pressure is maintained but almost no steam leaks.

Regarding green-tinted parts, whenever I've used black Rit dye, it has had a purple-black. When parts aren't perfectly dyed they tend to get a blue / purple hue to them and when the dye gets thinned out it has a red / purple color. Only once have I seen any hint of green in black Rit dye and that was when I was mixing it in acetone. Perhaps something about the vinegar or salt or citric acid or oil you put in caused the dye to break down / decompose into something with a green tint?

I'm traveling for work this weekend but when I get back I have a batch of about 12 puzzle to dye. It's probably too many parts to fit in the pressure cooker all at once so I probably have the opportunity to do a head-to-head comparison of regular boiling against the pressure cooker.

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 Post subject: Re: Using 15psi Pressure Cooker with Black Rit Dye to color
PostPosted: Sun Oct 20, 2013 9:58 pm 
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Joined: Fri Feb 18, 2000 8:50 am
Location: chicago, IL area U.S.A
I've used many pressure cookers for work and have lots of experience with them. Just to reiterate as Bmenrigh said, once you are up to pressure, the bleeder should barely be tipping. If it's moving too fast, the temp is too high and it is tough to tell if you will run out of water. If you do run out of water and you don't shut it off fast enough, you WILL ruin the pressure cooker and probably ruin all the parts inside. Also as the water level decreases, it takes less heat to keep bleeder moving, so you may have to slightly turn the heat down throughout the cook.

That still isn't as bad as if you run out of water while you are canning. The can WILL explode inside and cause the pressure cooker to explode! The best way to keep this from happening is to do it once - you will never do it again. :)

So just to reiterate, do not set it too hot and keep an eye on the bleeder. Pressure cookers can be very dangerous if you don't keep a close eye.

-d


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 Post subject: Re: Using 15psi Pressure Cooker with Black Rit Dye to color
PostPosted: Mon Oct 21, 2013 7:21 am 
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Joined: Sun Mar 15, 2009 12:00 am
Location: Jarrow, England
I must admit that I do not have to dye parts on an industrial scale, but I keep to the K.I.S.S. principal. 2-3 teaspoons of dye, a pan + lid of simmering water, a couple of capfuls of white vinegar and 20-30 minutes. Now I always get a nice deep black, even colouring (but I do stir the parts a lot) and very little run-off after rinsing with warm water (being careful to also wash out the insides). I know that I don't achieve a deep dye penetration, certainly less that 0.5mm, but that is enough for my needs.

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