Bandai 1/100 RXF-91 Kai

Here’s a real blast from the past, all up to date with a fully finished beam shield and sabre! The RXF-91 Kai might be old, but it still looks cool today!

If you know anything at all about Gundam, then you likely know that there’s a lot of it. The series that started it all aired in 1979, and we’re STILL getting models based on those designs today! So, you can imagine in the decades that have followed, there have been a lot of different things to make kits of. Through the ‘80s and into the ‘90s there were many OVAs as well as comic side stories, and amazingly a number of these got at least some of their designs made into model kits!

While the Formula 91 movie (which was, I believe, supposed to be a pilot for a new series that never materialized) wasn’t a huge success (and is a bit hard to follow) it was still beautiful and introduced a new generation of smaller Mobile Suits. This downsizing would be taken to the extreme when Victory Gundam aired, but the suits from F-91 aren’t a whole lot bigger. While the suits were small, the number of kits from F-91 wasn’t, and most of the major mecha from the movie got kitted.

There was more, though, to this time period in Gundam history than a lot of people in the West may know about now. While most fans do know about F-91, many are unfamiliar with MS Gundam F-90, a “F-91 prequel manga” that was published around the same time to help give some background to the universe in which F-91 takes place, as well as Silhouette Formula F-91 (SF-91), a manga side-story to the movie that uses different mecha but takes place at the same time, just somewhere else. As a result, there were three stories all resulting in model kits at pretty much the same time!

A common feature of the models from these series was their scale: 1/100. Because the new designs were smaller, it was felt that 1/144 wouldn’t do them justice and it would be hard to both make, and sell, the kits at this scale. See my HGUC F-91 to see just how small the kits would have been! Thus, modellers were treated to bigger kits than usual, with what was, for the day, very good detail and a lot of gimmicks.

I, personally, have always had a soft spot for the F-91/SF-91 and F-90 kits. When I was just getting into Gundam and anime in general, a local store, Cool Toys, had a lot of F-91 kits (this was about 1998-2000), as well as the odd SF-91 model. Thus, these were some of the first 1/100 kits I built. I’ve always been a fan of the Gundams from this era; they are very lithe and athletic, for the most part, and have a good “streamlined” sense of design. (For whatever reason, I have always called Gundams like this “Fight Gundams”. No clue why.) In addition, some of the SF-91 kits are interesting variations on the F-91 mecha, and I do love me some MS variants!

Probably my favourite Gundam from this time period though is the RXF-91 Gundam, the titular MS from the SF-91 franchise. This suit is quite “fight”, with very curved, almost muscular looking arms and legs, but a more conventional chest than the oddly-vented F-91. It also has a less “pillbug” backpack, and more conventional, round-bore Variable Speed Beam Rifles (VSBRs) on its back. This was actually the second SF-91 kit I got, and I loved it because it also had a two-piece beam shield. I believe this is still one of the only Gundams to do this (other than its stablemate, the Cluster Gundam, of course). Sadly, I built mine long ago, and by my current standards, it sucks.

I had a second chance, though! One of my students went back home one summer and emailed me, knowing I liked Gundams. He had found many local hobby shops still stocked some older ones. This was about 2005, so SF-91 kits weren’t easy to find. However, he found me all the F-90s and the only SF-91 kit that I’d never seen, the RXF-91 Kai. This is a “Kai” or “Modified” version of the RXF-91, with extra armour and bigger weapons. I snapped it up right away!

The one that didn’t get away! The RXF-Kai is an interesting mix of ’90s Gundam Design Elements, and having another chance to build one right was certianly appreciated!

Thanks to Vincent, then, let’s check out this little gem from the past!

NOTE: Just recently, the range of F-91 and SF-91 kits has been reissued! I must admit that I never thought I’d see the day when I could walk into a modern store and see SF-91 kits on sale. However, the Devil’s wearing his parka, and I thought this would be a great time to “jump on the bandwagon’ and take a look at one of these kits. While this isn’t one of the recent reissues, I guarantee you it is exactly the same. If you like this one, you can now go get one for  yourself, without sending an agent to scour all the hobby shops in Asia!

The Kit:

I got this kit in 2005, and it was already 15 years old at the time. Despite that, though, the RXF-Kai (as I’ll referto it from now on) was a good kit. It was very typical of its time, with fairly simple construction, full-on polycaps everywhere and, of course, a sheet of none-too-good stickers. As all kits of its time, most subassemblies come moulded in halves, and many subassemblies are not broken out into separate, differently coloured pieces. The reason for this is simple: System Injection!

Back in the day, System Injection was a BIG deal. System Injected kits were, like today’s kits, moulded in full colour. The difference was that all the colours were shot in the same piece! This revolutionary multi-gate, multi-colour moulding allowed a decently colourful replica of the kit to be built without painting, and was Bandai’s first attempt at creating a “near-zero effort” kit, finish-wise. Thus, the  upper body came in two halves, with the (now covered by armour) yellow chest vents, blue body and red bits all moulded together! It’s actually darned impressive, and it’s a shame I don’t have a good picture of the kit from before I started building it. Of course, that was long before I ever considered a website, so you’ll have to take my word, or look the kit up here:

While simple, the kit did have a few very cool gimmicks. One was the two-piece clear beam shield, which is something of a rarity, and as far as I know, only occurs in the Silhouette Formula series.  Another was improved posabilty over many other series, allowing some very interesting and dynamic poses to be achieved, if you wanted to. In addition, the kit could be build as the “non-Kai” RXF-91, since all pieces were included in this boxing.

The instructions were simple, and at the time I got this, the level of detail and “cool factor” were nearly equal to the big 1/100 HG Wing and X kits of 4-6 years later. Overall, then, quite a cool kit for the day, and light years ahead of anything else in the sci-fi field. As always, Bandai was determined to make Gundam Kits their showcase for advanced technology and precision moulding.

While not as advanced or as well-separated as newer 1/100 kits, like the RE:1/100 GP-04 (left), the RXF-Kai can still be made to look just as good when some patience and skill is applied.

Building the RXF-Kai:

While the model was extremely advanced for its day, by the time I got it, it had started to show its age. Nowadays, it would appear positively quaint to those accustomed to the newer HGUC and Master Grade lines. One of the biggest issues, as with all older Gundam kits, is “buildaround”.  Long-time Gundam builders will know exactly what I mean. “Buildaround” occurs when you have to finish one assembly and build another around it. This has been largely eliminated in modern kits (except many Zakus, it seems… c’mon, Bandai!!) but can never be factored out of a build completely. In the case of the RXF-Kai, though, it’s not as bad as it could have been. Unlike the F-90 kits, the SF-91 kits at least use a conventional “post-in-hole” polycap arrangement for the knees and elbows, saving a lot of grief. However, the shoulder armours, calf-booster covers, “golf shoe” ankle armours and even the massive Variable Speed Beam Rifles (VSBRs – the big guns on its back) all suffer from it.

This shows the completed VSBR; the canted part at the top is the piece I had to modify

In many cases, it’s not hard to work around buildaround. I was able to cut out some of the collars on the ankle and shoulder armours to allow it to just “snap on” once done; filing a lead onto the target part also helps. However, more surgery was needed for the VSBRs. Unlike the smaller, tubular VSBRs of the RXF-91, the RXF-Kai has larger, two-segment VSBRs that include a pivoting upper/rear segment. However, the VSBRs are also quite detailed, and it’s necessary to glue, sand, fill and really work on them to get them looking right. Thus, I needed a way to be able to do all the work, and pop the end bit in once both halves were done.

To achieve this, I cut off the posts on the smaller components, and installed an “axle” (or rather a support rod) in the larger part of the VSBR. This formed something to which I could attach the smaller part once it was done, and I could close up the larger part with glue and work on it. I then cut off the pivot posts on the upper part, and also cut out the bottom of the piece, using a round file to contour it to the diameter of my mounting axle. Thus, when the smaller part was done, it would just clip over the rod and hold position.

On the right is the original part, while on the left is the modified part with the channel cut into it. Snapping the latter into place is simplicity itself, compared to building around the original!

This worked really well, and I also modified the beam shield by cutting out the mounting holes so that the clear parts could be inserted into the central core. Since the central core is the biggest of any on a beam shield equipped Gundam, and required a lot of careful painting, this was a plus. Unfoshield! GAAAHHH!! It’s not like I can run down the street and get a new one. This kit was old when I was building it, and I’ve still never seen another copy!rtunately, I forgot how brittle the old clear “beam plastic” on Gundam kits could be, and it cracked my beam definite

Thankfully, the past came to save me! Long ago, I’d purchased and built the RXF-91, and it had long been a favourite of mine. However, it was looking its age, having yellowed and having been built long before I had improved my techniques. Thus, I stole its clear beam piece, which I had managed, years before, to safely cut to allow for removal! Phew!

Here are the modified beam shield halves, cut to allow easy insertion to the shield projection unit once all painting is done.

These were really the only difficulties in building this kit that I encountered, and other than the fit of the parts being less precise and requiring more sanding than a modern kit, the build went quite well. One thing I did change was the beam sabre. Being an old kit, the RXF-Kai came with single-piece, solid beam sabres. I wanted a nice clear blade like you’d see in a more modern kit, to match the shields. I think I stole a spare sabre blade from my 1/100 Freedom, actually, and used it. I cut off the original blade and drilled a hole in the handle to allow the new blade to be inserted. This is a simple but effective upgrade, and I was very pleased with it.

Painting and Finishing:

Paiting the RXF-Kai was very straightforward, for the most part. The white bits were primed with Colourplace rattlecan Flat White and the rest with Colourplace Grey Primer, also in a rattlecan. I used a modified version of Tamiya Flat White that I call “Gundam White” for the white parts. Gundam White is a mix of Tamiya Flat White and some Testors Model Master Acrylic (MMA) Flat White with a very light hint of Tamiya Purple and whatever bright blue you have on hand. The “hint” is so light that I put it into the mix by dipping a toothpick into the blue (and purple, using different sticks)  and then dragging the wiped-off stick through the top surface of the white paint.

I used MMA Ford/GM Engine Blue with a bit of white in it for the blue parts, MMA Guards Red for the red and the dark black parts are Virsago Black, which is a dark black/grey hybrid. As always, I used Jet Exhaust with orange internals on the engines, and MMA Steel on the various gun barrels. I used a black wash of Citadel Baddab Black (R.I.P. – I constantly miss this colour) on the metallic parts. I did use a bit of imagination and painted the leg breathers in Steel; they were supposed to be white, but I wanted some metallic shades on the legs, too.

Clearly, I didn’t use any of the stickers, because they’re no better then than they are now.

From the back, you can see the original, “un-beamed” shield and all the detail work on the VSBRs.

Upgrading the Kai:

While the Japanese designation “Kai” means “Modified”, or more correctly “Upgraded”, my RXF-Kai, as built still had room for improvement. I had a good paint finish and I’d built it well, but it still couldn’t stand up to its more recently built cousins.

One thing that did need some work was the beam shield. I used to just leave beam shields alone, when I was less experienced and didn’t have an airbrush. However, since I’ve gotten better, I’ve taken to adding “energy effects” to my beam pieces. Thus, years after I finished this mech, I decided to get dangerous. I pulled out the beam shields and decided to “upgrade” them to my new, current standard. One mistake would spell the end of one of the coolest features of the kit. However, if it went well, then the mech, build years before, would look the equal of its most modern peers.  I wrestled with this question for a few months before deciding to go for it

While not the greatest photo, you can see the original “un-beamed” shield and sabre quite well in this photo, taken years ago after the model was first completed.

I put down a coat of Mr. Surfacer White where I wanted the “energy” to be “hottest” (i.e. near the projector and along the “rays”) and faded it in very lightly to make the shield a bit translucent, rather than transparent.  I then oversprayed with a couple of light coats of Future mixed with Jacquard Interference Violet and Interference Gold pigment. This is a great “beaming” paint; it dries pinkish, tinting the white “energy” and making it look like it is “inside” the beam envelope. It also adds a pearlescent sheen, which just plain looks cool.

In this newer photo, you can clearly see the white “energy” added to the base of the sabre and the rays of the shield!

Thank goodness it worked! I breathed a sigh of relief. Then I figured I’d better do the same to the sabre. This was nearly no-risk, since I have a lot of 1/100 beam sabre blades! With this component finished, the RXF-Kai was able to step into the present and hold its own with all its other brothers. It’s amazing what a little bit of extra paint and patience can do for a kit, eh?


 The RXF-91 Kai is an interesting piece of Gundam history. The sidestory from which it comes is very little known outside of Japan, and I’m sure even many current Japanese fans haven’t even heard of it. The designs from Silhouette Formula 91 are very much of their time, and make a neat “missing link” between the conventional MSs of Char’s Counterattack and the amped-up/shrunken-down suits of F-91 and Victory Gundam. Not only that, but they represent an interesting period in the moulding of kits, touting System Injection’s advancements, only to be left behind with full colour moulding of separate pieces not too much later in time.

I personally love the F-90 and SF-91 mecha. They look great, and while they appear to be simple kits, there’s lots there for a modeller to have fun with. There are a lot of verniers, vents and barrels to pick out and paint, adding considerable personality to the model. Plus there are good opportunities to practice your ingenuity and avoiding buildaround and other decidedly “old skool” problems that more recent devotees to the hobby might not have encountered before.

That’s really the only gripe I have about the RXF-Kai. It’s a great kit given its age, but it’s not for everyone. If you’ve been at this a while, you can handle it. If you’ve got good, basic modelling skills, you can handle it. If you’re used to the ease of newer HGUC and Master Grade kits, and you’re not much of a painter… you’re dead. This kit, despite the System Injection, will not really reward lazy modelling or simple snap assembly. This is an old kit; you actually have to MODEL it. Funny how that works, eh?

Overall, though, I love this kit, I love how it turned out and I love that I had to dig into my old bag of tricks to do it. Car and Plane builders aren’t the only ones who can get a retro-rush from old kits! If you like what you see, you can now find one nearly anywhere Gundams are likely to be sold. I encourage you to pick it up; it’s good exercise and it’s something most people won’t recognize today. That’s 10/10 where I live!

Despite being a smallish mech, the RXF-Kai is pretty thick thanks to the VSBRs! Note the pearlescent reflection of the newly “Beamed” shield.

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