So, what's this brilliant idea I came up with all about then?
Our brethren in the plastic aeromodelling world have had access to precut paint masks for ages. Essentially these are thin plastic sheet with a low tack adhesive backing, designed to make it a doddle to paint canopies and wheels. You pop the cut part out, stick it on your model, squirt paint all over it, and remove the mask when dry. They're a use-once deal. They are discarded after use, unless you're careful and canny.
Anyway, I got to wondering how I might replicate the idea for the masking on these pesky coaches. After the failed attempt with traditional masking tape - although that was more down to the paint than the masking, since I have used the same technique on previous coaches painted with an airbrush - I needed something that would be happy to remain in situ during the painting process, but crucially not risk peeling the masked paint off when it was removed.
As I dozed off to sleep, pondering the next morning's workbench duties, I thought "how about aluminium cooking foil and Spraymount?"
Here's the reasoning: Spraymount (in the blue cans) is meant to be a temporary fixative. Residue can be cleaned off later with lighter fluid. The amount of tack on a hard surface should be sufficient to hold the mask in place yet let it be removed with minimal damage after the unmasked area has dried. The ally foil is forgiving enough that, with care, it can be wheedled into the nooks and crannies around hinges, corrosion strips, window frames and so on, and give a nice crisp edge to the masked area.
Nothing for it, but an experiment.
Next day, out came the calculator, a roll of kitchen foil, a sharp scalpel and a straight edge long enough to trim out a length of foil.
The panel to be masked is, by my calculations, 442mm long and 27mm wide. I marked out the panel ends and top edge on the coach side. The top edge above the window frames on the JLTRT MK2B/C bodies is 2mm wide, so I marked halfway. Fine pencil lines showed where the mask was to fit. 27mm let the masked area fit down to the bottom of the commode handles, which is what I got wrong last time.
One potential snag with cutting foil is, well, snags. It's easy for the blade to catch the foil and tear instead of slicing. Getting a nice square edge to start with was not as difficult as I thought it would be. Once I had a datum, I could measure 27mm off and slap an 18in ruler down across the width of the roll. In this case, the roll was long enough for a bit of excess each end of the mask, which was handy as will become apparent later. Cutting with the blade held at a low angle in short passes, while firmly holding the straight edge to prevent the foil snagging, and I soon had a couple of strips trimmed out.
I had just got a coat of Spraymount on them, when Mr "Barking" Beare called. We had a nice chat about life, the universe, and using aluminium foil for masking purposes. He reminded me that as I worked the foil around details it would shrink in a linear fashion by a small amount. To counter this, I suggested I would split the oversize length of the strip into three, and stick the end pieces on first allowing the third panel to overlap across the centre.
Anyway, would you believe it? It only worked!
First, the strip was stuck to the cutting mat, aligned along the grid lines to be reasonably square. I nicked out 45 degree corners, which will be filled in later as the radiused corners, on one end.
With the mat hard against the edge of the bench, I used an engineering square to mark off straight cuts for the three panels. I used a body side to align the trim marks with spaces between windows, so no overlap would occur across a window or door panel.
Carefully lifting each trimmed strip, I aligned them on the side. I then set about with a cotton bud to gently push the foil into the contours as best as possible, and to ensure the edges were stuck down to avoid too much paint creeping under them.
Eventually, one whole side was masked. If anything, the entire process took less time than using masking tape. Any areas where the foil was punctured, such as across hinges, could be covered with a dob of masking fluid. As it happened, I managed to avoid any punctures.
With one coach masked, I disappeared into the "booth" to get a test coat of blue on.
You may recall references to the Advanced Paint Drying Facility (aka our airing cupboard)? Well, getting damp body sides down the loft ladder and into the APDF is tricky, so I have tended to leave them to dry sufficiently before transporting. This time, I came up with a wheeze.
We have an electric oil heater I use to keep the cold at bay when working up in the 'shop. With the plastic lid from the "booth" going spare (usually used as a cover to avoid grollies dropping on wet paint), it was positioned in such a way it caught the warmed convection from the heater. Behold! APDF Quick Drying Unit:
Using this lash-up, sides not only got dried fairly quickly, but also warmed up. This means, as any regular airbrusher knows, subsequent coats go on and dry almost as soon as they hit the side. Well, not exactly, but you get the idea. The whole painting process is speeded up no end.
Anyway, the first sides were left overnight (with the heater off) to harden. Checking them this morning, and I saw that it was good. Apart from one or two dust specks, the masking worked a treat.
Here is the scene after this morning's efforts on one SO and the BSO, and some remedial work on the ends. They have since had a further coat or two, and are about the right depth of colour now. The second SO will get a faded blue finish, just to be different.
Inevitably there will be sneaky bits of blue paint under the masking. I am prepared for that, and I know full well that some careful brush retouching will need to take place, probably while I'm putting the white line on.
We're getting perilously close to being able to fit glazing and put bodies together!
.
