Keeping particles in suspension

[jbb]

I have taken a fancy to mixing gold metallic powders into my ink for dip pen writing. It creates a very pretty effect. The powders (which I believe are mica) want to sink to the bottom rather quickly so it is necessary to keep mixing the ink all the time. Is there anything that might help keep the particles in suspension? Would salt work? Salt would probably ruin my dip nibs quickly, right?

[Zoe]

No expert, however, I have used metallics and find the same situation. I just keep shaking! IMO, I think adding something, salt or otherwise, might be more of a disturbance than a positive additive factor.

 

Interested in hearing what other experienced users have to say!

Edited August 24, 2008 by Zoe

[BillTheEditor]

No salt! Stir often and vigorously! Think about the movie "The Karate Kid" if it helps: Wax on! Wax off!

[tfwall]

You're kind of limited due to the requirements for ink not to damage paper or pen.

 

The main ways you get something to stay in solution are:

-reduce the dye particle size. If you can get it down to colloidal sizes, then Brownian motion will keep the dye in solution.

-change to solvent. Different solvents can more easily solvate the particles and drag them into solution.

-change the pH. Putting an electrostatic charge on the particles often allows them to more readily enter solution.

-add a co-solvent. This is something that can both dissolve the dye and be is soluble itself in the primary solvent.

-mechanical agitation.

 

Perhaps if you strained out the dye, you could mill it further to reduce the size. It is certainly feasible if you have the time, inclination and instruments.

 

Changing the solvent, the pH or adding a co-solvent is much riskier because you don't know what is in the ink already.

 

Mechanical agitation is what you are doing now.

[jbb]

You're kind of limited due to the requirements for ink not to damage paper or pen.

 

The main ways you get something to stay in solution are:

-reduce the dye particle size. If you can get it down to colloidal sizes, then Brownian motion will keep the dye in solution.

-change to solvent. Different solvents can more easily solvate the particles and drag them into solution.

-change the pH. Putting an electrostatic charge on the particles often allows them to more readily enter solution.

-add a co-solvent. This is something that can both dissolve the dye and be is soluble itself in the primary solvent.

-mechanical agitation.

 

Perhaps if you strained out the dye, you could mill it further to reduce the size. It is certainly feasible if you have the time, inclination and instruments.

 

Changing the solvent, the pH or adding a co-solvent is much riskier because you don't know what is in the ink already.

 

Mechanical agitation is what you are doing now.

 

...not to mention my mental agitation. It sounds like I'm stuck mixing the ink a lot. Wax on! Wax off!

 

[Sholom]

This is an issue of suspension, not dissolution. There are ways to suspend metallic particles in liquids like inks, but for the size particles that give the biggest visual effect, the only ways I can think of involve altering the "viscosity" (really rheology, but that's a subject for a long post some day) of the ink. A water-soluble high molecular weight polymer such as xanthan gum or the right grade of methylcellulose would not keep the particles suspended indefinitely but would slow the rate of settling after the ink was remixed. The trade-off is that the ink would feel "thicker", might be slow to flow, and would probably dry noticeably more slowly. Getting this sort of problem resolved is often very much a trial-and-error thing involving balancing a bunch of trade-offs. In terms of household items that might work, all I can think of off hand is liquid pectin (as in jelly making). Keep shaking!

[jbb]

This is an issue of suspension, not dissolution. There are ways to suspend metallic particles in liquids like inks, but for the size particles that give the biggest visual effect, the only ways I can think of involve altering the "viscosity" (really rheology, but that's a subject for a long post some day) of the ink. A water-soluble high molecular weight polymer such as xanthan gum or the right grade of methylcellulose would not keep the particles suspended indefinitely but would slow the rate of settling after the ink was remixed. The trade-off is that the ink would feel "thicker", might be slow to flow, and would probably dry noticeably more slowly. Getting this sort of problem resolved is often very much a trial-and-error thing involving balancing a bunch of trade-offs. In terms of household items that might work, all I can think of off hand is liquid pectin (as in jelly making). Keep shaking!

 

So then would the only way to keep the particles in suspension be to thicken the liquid in which it is suspended?

 

[Robert Hughes]

This is an issue of suspension, not dissolution. There are ways to suspend metallic particles in liquids like inks, but for the size particles that give the biggest visual effect, the only ways I can think of involve altering the "viscosity" (really rheology, but that's a subject for a long post some day) of the ink. A water-soluble high molecular weight polymer such as xanthan gum or the right grade of methylcellulose would not keep the particles suspended indefinitely but would slow the rate of settling after the ink was remixed. The trade-off is that the ink would feel "thicker", might be slow to flow, and would probably dry noticeably more slowly. Getting this sort of problem resolved is often very much a trial-and-error thing involving balancing a bunch of trade-offs. In terms of household items that might work, all I can think of off hand is liquid pectin (as in jelly making). Keep shaking!

 

So then would the only way to keep the particles in suspension be to thicken the liquid in which it is suspended?

That's what is done in hand papermaking. Cellulose fibers tend to fall to the bottom of a vat, so a thickening agent such as methylcellulose is added and the vat is stirred regularly.

 

[jbb]

I continue to be fascinated by writing in metallic gold ink. I have not come up with a way to keep the particles in suspension but have discovered that if I add more Gum Arabic the particles stick to my nib more making it easier to write.

[Titivillus]

You're kind of limited due to the requirements for ink not to damage paper or pen.

 

The main ways you get something to stay in solution are:

-reduce the dye particle size. If you can get it down to colloidal sizes, then Brownian motion will keep the dye in solution.

-change to solvent. Different solvents can more easily solvate the particles and drag them into solution.

-change the pH. Putting an electrostatic charge on the particles often allows them to more readily enter solution.

-add a co-solvent. This is something that can both dissolve the dye and be is soluble itself in the primary solvent.

-mechanical agitation.

 

Perhaps if you strained out the dye, you could mill it further to reduce the size. It is certainly feasible if you have the time, inclination and instruments.

 

Changing the solvent, the pH or adding a co-solvent is much riskier because you don't know what is in the ink already.

 

Mechanical agitation is what you are doing now.

 

Unfortunately you don't want the particles in solution but rather suspension which means increasing the viscosity of the liquid since messing with the particles is going to be tricky.

 

 

Kurt

 

[Titivillus]

I continue to be fascinated by writing in metallic gold ink. I have not come up with a way to keep the particles in suspension but have discovered that if I add more Gum Arabic the particles stick to my nib more making it easier to write.

Gum arabic should increase the viscosity of the ink as well. SO doing two things at the same time

[tfwall]

You're kind of limited due to the requirements for ink not to damage paper or pen.

 

The main ways you get something to stay in solution are:

-reduce the dye particle size. If you can get it down to colloidal sizes, then Brownian motion will keep the dye in solution.

-change to solvent. Different solvents can more easily solvate the particles and drag them into solution.

-change the pH. Putting an electrostatic charge on the particles often allows them to more readily enter solution.

-add a co-solvent. This is something that can both dissolve the dye and be is soluble itself in the primary solvent.

-mechanical agitation.

 

Perhaps if you strained out the dye, you could mill it further to reduce the size. It is certainly feasible if you have the time, inclination and instruments.

 

Changing the solvent, the pH or adding a co-solvent is much riskier because you don't know what is in the ink already.

 

Mechanical agitation is what you are doing now.

 

Unfortunately you don't want the particles in solution but rather suspension which means increasing the viscosity of the liquid since messing with the particles is going to be tricky.

 

 

Kurt

 

Same thing for this discussion. Ideally you'd like like a colloidal suspension to avoid the whole separation issue. My recommendations 1-4 will do that, barring that you're left with mechanical agitation.

 

[BillTheEditor]

If you want to thicken the mixture, another way to do the job is to simply leave the cap off the container for a bit. Check frequently to make sure you haven't let too much of the liquid evaporate.

 

If you are going to add gum arabic, add very little at a time -- a drop or two if liquid, a couple of crystals at a time if using solid g.a. Stir vigorously and test before adding any more.

 

In either case, stir. As long as your metallic powder isn't colloidial size particles, you are going to have to stir the mixture periodically.

 

Should you ever choose to use gold paint instead of mixing metallic powder into fountain pen ink, be careful what you add to it. If the solvent isn't water, gum arabic isn't the right thickener.

[Titivillus]

Same thing for this discussion. Ideally you'd like like a colloidal suspension to avoid the whole separation issue. My recommendations 1-4 will do that, barring that you're left with mechanical agitation.

 

Yes but your four suggestions are not going to be easliy done and something that needs a wet chem lab. whereas upping the viscosity slightly could get you instant results. And for that matter there is no guarantee that a colloidal suspension would give you the same gold shine as larger particles- it might just come out tan instead.

 

 

Kurt