Help - matte medium problem

[nachoman]

I have a goal of having at least one "completed" scene on my layout - that means putting down ballast. I always used white glue in the past, but this time I opted for matte medium as glue. The waterproof quality of the dried medium appealed to me as this is the first time I have hand-spiked rail to wood ties - I want the ties and trackwork to be impervious to moisture changes. Since this is a yard area, I dug up and sifted dirt from my yard to use as ballast.

Here is my problem: I used liquitex brand matte medium from the craft store. It is somewhat on the low-end price wise, and I thought it would work fine for bonding ballast. I mixed it about 1 part medium to 4 parts water and a few drops of dishwashing detergent. I sprayed the area with water and detergent, then applied the ballast glue. This is the same procedure I used when using white glue. When it dried, it left a white "residue" in places on top of the ballast.

Doing a little research, I read that some matte medium has talc in it that may cause this problem when diluted. Some people write that ModPodge brand is cheap and does not do this; perhaps I should try a different brand. Has this happened to anyone else, and does this explanation make sense?