by: Kimmo Happonen [ ]
No single element manages to run the gamut of emotions with modelers as does photoetch. It is either loved, hated or viewed as a necessary evil. It can provide levels of detail and frustration that other media can't. One of those frustrations is how well, or poorly, paint adheres. Especially with fine grills and mesh. There is simply nothing more annoying than having built, painted and weathered a lovely model and discovering tiny, very shiny, flecks where paint has failed to adhere to the photoetch. AK Interactive has a solution, literally. Brass Photoetch Burnishing is a liquid that will blacken brass and other metal alloys and theoretically, improve paint adhesion. So, does it actually work? Let''s find out.
The product comes in a fairly sturdy 100 ml plastic bottle with various warning labels and a brief description on how to use it. Clean and soak the photoetch for 3-5 minutes (or longer), agitate, and that's about the extent of the instructions. AK's website is even less informative. Opening the bottle, you will notice the distinct odour of nothing. A pleasant surprise. Needless to say, do not drink this stuff or splash any about. Clean up any spills or splashes immediately to prevent staining, and thoroughly wash your hands after use. Fully armed with the wealth of knowledge gleaned from the label, I decided to give it a try.
Since the product is in a plastic bottle, I figured a plastic takeaway container would do. I can happily report that the liquid did not damage the plastic, and that the previous contents were indeed, delicious. My chosen test subjects were scraps of photoetch frets and a leftover screen and strap from various manufacturers. I duly placed the pieces into the liquid, rocked the container a few times and waited the allotted 3-5 minutes, or the length of a Police track. I placed the pieces on a paper towel to absorb excess liquid and let them dry on the air. I used a set of stainless steel tweezers, no staining was evident, however, rinse your tweezers of choice afterwards to be on the safe side.
All the test pieces did indeed blacken quite nicely, and did so without any surface prep. And as you can see, the liquid remains quite clear after use which suggests that you may be able to reuse it, at least to some degree. I took a moistened cotton bud to one of them to see what would happen. To my surprise, the ”black” rubbed off, however, the brass definitely had the shine removed.
The next test was to dab a little liquid directly onto a fret. Again, it did blacken. And again, it swabbed off. So I repeated the test with a more generous application. This time the black remained, as did a slight ridge from the pooled liquid.
Next up, I burnished a few pieces with a toothpick. The black was removed as was the nickel plating on the Eduard fret. The brass underneath was nicely tarnished though where I hadn't used the point of the toothpick.
And lastly, I primed a few pieces with Vallejo Grey primer to test adhesion and whether the black would affect the paint. I primed several pieces, and a set of tread plate that was treated and not treated. On reflection, I should have tested with regular Vallejo paint as well because Vallejo primers tend to stick quite well as it is. I don't use enamels so you will have to perform your own tests to see if there is any improvement or not. Letting the primer dry for about 30 minutes, I scratched the surfaces with a toothpick. Not surprisingly, the primer started to come off both the untreated and treated surfaces. Leaving them to dry for a few hours produced more normal results. Vallejo primer needs to cure overnight to ensure good adhesion. I didn't notice any adverse effects to the paint.
Based on these initial tests, I would recommend this product as it does seem promising. Experimentation will be needed to determine how long to leave parts soaking to get the best level of darkening for different alloys. I suspect that the longer you leave the parts to dry, the less likely the black will rub off. The suggested retail price won't break the bank either, I paid a couple of Euros more for mine from an online shop, so do a little price comparison if that's a concern.