So I went ahead and sprayed a terrain layout with watered down matte medium not realizing that unless you separate the talc it leaves a horrid white residue that does not seem removable by water (after the water dries completely it appears right back). It is seeped deep in the rocks but not really anywhere else.
Does anyone know how to remove the residue (now that it is there) without ruining the paint on the rocks? Since water seems to hide the residue I am thinking about just spraying on a Satin or gloss varnish then maybe spraying a matte varnish on over that to try and hide the shine. I was also thinking that maybe the residue is soluble in something, but I know not what.
Any help restoring this layout would be wonderful! It was coming along so well till this.
I was thinking maybe an acrylic remover (as this is what the matte medium is), but I worry the woodland scenic paint might be the same stuff and remove it too.
I would try some Dullcoat. or other clear coating. You say that when wet it disappears, the clear may hide it or at least make it not as noticable. Practice on an inconspicuous arae first. For future reference, do as Dave Frary does w/ the matte medium. Dilute 1:1 w/ water in a large preferably glass sealable container and allow to sit for a few days maybe as much as a week. the talc will settle to the bottom. Pour off and decant into sealed container for use. Further dilution will be required of coarse to you get that ratio you like to work with 3:1 or 4:1. One quart will produce about a gallon.
Denatured alcohol will remove matte medium. You may be able to mist it on to cleanse it off the rocks. However, denatured alcohol could affect the other scenery so test a small spot first if that might be an issue for you.
Then there’s always just covered the offending spots with some ground cover as an alternative.
Thanks you all! I have tried another varnish (both satin and gloss) in a test area, but that does not seem to work any more than dulling the white slightly and making it shine. I think I might try some of the denatured alcohol on a test rock and see if that works. Otherwise I am going to have to result to a few hours of re-painting some of the area and ground-covering it. Might try Isopropyl alcohol if denatured fails.
I’ll try and remember to post the results with the alcohol.
The white talc residue problem is one reason I don’t use matte medium for scenic adhesive. I never found the additional flexibility it supposedly provides to be of any real benefit for durability or noise reduction. Diluted white or yellow glue adheres just as well and there’s no preparation necessary to settle out something suspended in the glue. Plus either should be less expensive than matte medium.
While I’ve never had any problems with white residue when using matte medium, my experiences were similar to Rob’s as far as the supposed benefits of matte medium over white glue. I found both to work equally well, but a gallon of white glue is a little more than half the cost of the same amount of matte medium.
I’m also not a fan of spraying any such material - it’s not only inefficient, but it puts the glue or matte medium on a lot of surfaces where it shouldn’t be.
My guess is that the white residue was left because you didn’t sufficiently pre-wet the area before applying the matte medium.
Well unfortuantely isopropyl worked but it also removes woodland scenic paints underneath. i have not tried denatured alcohol but I suspect simmilar results so I am just going to paint over it myself. Thanks for the help though!
I occasionally had issues with the white residue before I learned to dilute it, let it settle, and decant the adhesive, as noted above – although I go ahead and dilute it to 4:1 before letting it settle. I also add 2 drops of dishwashing liquid per cup of solution when mixing.
As some have pointed out, the white residue is due to the talc which is used as a dulling agent. However, when properly mixed, the ratio of talc isn’t high enough to cause spotting. So my guess is that you had some chuncks of talc in your solution.
So my advice for the future: 1) Let your matte medium solution settle, and decant it to remove most of the talc; 2) dribble it using a medicine dropper, pipette, old glue bottle, etc. rather than spraying (or, if you must spray, protect anything you don’t want to get matte medium on it with newspaper, an unfolded cereal box, etc.). For me, the cost tradeoff isn’t an issue, because I prefer matte medium to white glue for both it’s flexibility (especially once the glue has been there for a while), clarity (once the talc is removed), and consistency in its undiluted state (I paint my landscape with full strength matte medium prior to putting down a first coat of turf).
As far as fixing this problem, many rocks have white calcite veins and spots anyway, so it might not really be an issue (depending on how significant it is). Your best bet, however, is to repaint the rocks.
If you’re worried about the white residue on rocks only, try a very thin wash made with India ink. It settles into the cracks and helps give them depth. I finish mine by dry brushing with antique white acrylic paints This highlights the rocks, as well, adding to the depth.
What I was going to suggest except for using Dave’s black wash (an diluted acrylic formulas from his book). Also, I have never found this white residue but then I know from art school that you have to really mix this stuff up, even before you dilute it.