I don't wish to derail the thread by any means, but this talk of fumed silica has been very interesting and has started me wondering if it might be useful for something else; namely dye-imbibition.
Because fumed silica is used in micro-porous inkjet papers to accept pigment inks (which I realize are fundamentally different than dyes), I wonder if the same high surface area property that makes it suitable for this might act as a sponge/trap for dye solutions; thus reducing diffusion in non-mordanted receiving papers.
Just a thought... wanted to mention it. It's exciting to apply new materials to old processes.
I think you would get some severe dot gain with it due to its massive surface area with the inkjet.
What I need to do with the fumed silica is to do a sheet with the FS and a sheet which has had a 2% Pot Ox acid soak.
The more I look at the prints I've been doing, the more I wonder how much of a difference on Platine it makes vs a good solid coat of PT.
At the risk of wandering too far down the digital road...some inkjet printers are dye-based (including some relatively high-end ones), and there is some evidence that dye migration is an issue, albeit significantly reduced from the days of swellable polymer papers. But from my understanding, this is something that tends to happen over longer periods of time (weeks to months). Google is your friend on this...
Originally Posted by holmburgers
But if a dye-imbibition print could be made relatively quickly, before the dyes had a chance to migrate appreciably, then perhaps a mordanting bath after the print was complete might arrest the migration? The biggest issue might be the matrix getting bonded to the substrate during transfer. After all, some people use micro-porous inkjet papers as the final support for carbon transfers.
Just some more (now fairly off-topic) thoughts...
Originally Posted by Dan Dozer
Let's hope we can help you out with this. Were you PT or PD printing? I've seen a lot of testing with this stuff both in liquid and dry (I find dry much easier, but to each their own) and haven't seen that reaction before. It makes me wonder what's different in the procedure over the other's that have had quite solid success.
I use the NA2 method so it's PT/PD. I think that the spotting problems are due to the foam roller and possibly the density of the paper. Both papers I used are heavy weight and don't necessarily soak up a solution as fast as thinner paper. I'm thinking that maybe the silica solution is sitting up on the surface of the paper. Note that bubbles are forming when I try to coat and it's not that easy to get rid of them during the coating process.
Originally Posted by Klainmeister
If this is the case, perhaps the wet coating method just isnt' all the great for the thicker paper. Also, I didn't really see any difference in D-max at all on either paper.
To me, it does indeed sound like the paper isn't coating as well as others. The spotting sounds similar to air bubble issues we experienced at first. I'd recommend getting a sample of the dry powder and giving it another shot. When using the dry powder, you only need a little bit to spread about and I find it easier to see the sheen on the paper as well as avoiding any sort of contamination. the increase in DMAX is very apparent when we first used Stonehenge, which isn't a heavy weight paper. Let me see what we can find regarding COT 320.
I thought I'd jump in here for a moment.
All of the comments here are useful and understandable. The coating technique is crucial!!!
My assistant, Madelyn Willis and I or coincidentally are doing a silica demo at Christopher James' workshop at the Santa Fe Workshops tomorrow.
As I have said in the notes on the process, there are a ton of variables to test, and we will learn more from the field use than attempting to test a million different ways to use the material.
Most likely you will need a good paper to start with and one that will handle some extra brushing of the the sensitizer.
We have found that roller coating of the silica works best and eliminates the extra drying step.
The key is getting enough, but not too much silica, on the paper. If the roller is fully charged and has been used for a number of prints, then around 1/2 teaspoonful to an 11x14 sheet is about right but this is going to end up being more of an intuitive issue with the worker. (It's art!)
The key is, after roller coating the silica, to brush the sensitizer on rilly rilly well. OK, now my hearing is shot to hell, so when Maddy is with me during the coating she says she hears the brushing start to squeek with each brush stroke, which is done at the end, lightly and briskly. A very high pitched squeek comes with the brushing. That may not happen with all papers but it does with COT and Platine.
Streaks in the final print are likely:
Too much Silica or Alumina
Too much senitizer -- at first it doesn't seem as if you have enough but it does tend to spread out as you coat.
Not brushing long enough, you need to go to the matte stage and then more. At least till it squeeks and then some. It is strange but it seems like you really need to brush it in.
So I suggest starting with a small amount of silica, being careful not to get too much sensitizer on, enough, but not where it gets sloppy, and brushing the print until it is matte and then squeeks, and then some.
I fully agree with the matte look although I've not heard it squeak. :)
Originally Posted by richsul
Has anyone done tests with Fumed Alumina from B&S ? Reading the documentation regarding its use, it has as ph as low as 4.5 and thus might negate the use of acidification for troublesome papers which would be useful. Will be testing it over the next couple of weeks. Would like to get BFK working reliably.
Originally Posted by Davec101
The affects on the image are almost the same. If I recall (it's been a while), it had a cooler effect than the fumed silica. Dmax is increased just as well, looks excellent.