I thought that starting with the Interstage/S-IVB/IU would be easier than starting with the S-IC/S-II: the S-IVB unit is much smaller than the S-IC unit, and it made at least some sense that it would be quicker, easier, and a good place to check out masking technique.

I was wrong. I was very wrong.

The S-IVB unit has a ton of detailed masking to be done. There’s the Interstage, a non-cylindrical conic section; there’s the top of the tunnel cover; there are the zillions of antennae on the IU; there’s an irregularity in the roll pattern on the S-IVB for an antenna, there are the retro rockets on the Interstage. It seemed endless. To top it off, the stringers are finer pitched than those of the S-IC. In retrospect, it would have been far better to mask and paint the S-IC unit first.

Regardless: it’s done. The S-IVB unit is now masked, painted, and unmasked. I need to do only minimal touch-up. There are a few places where I tried out Apogee’s recommendations of using a fine-point permanent marker to delineate the white and black roll pattern segments, filling with the marker, and masking so any black paint bleeding under the tape would bleed into an area already marked up with black. Well, the marker’s ink wicked a little along the stringers, so I changed to straight masking (tape and liquid mask), and that worked wonderfully. The biggest areas for touch-up from these techniques are a couple of the very small antennae on the IU where a bit of black paint ended up on the white during the unmasking, and a couple small spots where I didn’t get the liquid mask on just square.

On the whole, I am very please with the results!