During my assembling process of my first model I was wondering: how much cement is the right amount? I use Tamiya extra thin cement and I sometimes put cement on the piece itself and once I had it in place I put more cement on it all the way around. Sometimes it felt like a piece is coming lose and I added even more cement.
Now after everything is completely assembled and done (not painted yet), I can see the cement on almost all spot shimmering.
So my question is: will all these spots be covered after priming and painting, or will this bite me in my back because it will be visible later, even after painting? It might be not too relevant for my Panther tank, but I do have a Porsche car that I might want to assemble soon and a car is much finer and more sensitive when it comes to imperfections in the paint etc.
I just want to prevent myself from messing it up from the beginning.
Shimmering is fine. If you apply so much that it visibly crazes the plastic, it’s too much. Generally with Tamiya extrsa thin, touching the pointof that tiny brush to joint once or twice is sufficient.
For a finish like a car you can always go over it with a 2000 grit cloth if you’re worried.
Hold the parts together for a few seconds after applying the cement. Judge how well it’s working by checking to see if the contact surfaces have become soft and “sticky.” If they have, you’ve generally applied enough cement. Press the parts back together so they have good contact and the correct alignment. Leave to dry (usually an hour or so is good for careful handling, but overnight for full curing).
Until you have some experience, you can always test your cement by cutting a couple of pieces of the sprue and gluing them together. Trim the contact surfaces for good contact, and then apply your cement. Follow the above suggestions to see how the cement works on that particular plastic.
After a few experiments and a kit or two, you’ll get a good feel for how some particular cement works. You’ll find that not every brand and viscosity works exactly the same, and you might find that keeping a couple of different brands and / or viscosities is useful for different jobs and sometimes for the different plastics used with different kit brands.
Understand that the plastic cement works by dissolving the plastic which then combines / mixes together at the joint. The solvents evaporate leaving the plastic parts essentially merged into a new, single mass. Too much cement leaves the joint too wet and soft and the parts will not adhere to each other. Too little and the joint dries before the plastic has dissolved enough to combine into a new, single mass. Way too little, and the plastic might not dissolve at all before the cement evaporates. Some cements have an amount of plastic already in solution and are thus more viscous and “sticky” right from the bottle. Others are essentially straight solvent. The straight solvent types often have drying retarders mixed into them to moderate how fast they evaporate to modulate their working time.
Each type has its pros and cons, and each is better for some jobs and not as good for others. A lot depends on your own building methods and preferences, and only time and experience will tell you what works best for you in every situation.
If you pass out or start seeing little pink elephants then its too much. As the saying goes “a little goes a long ways” applies very good to glue, pun intended.
I wanted to chime in here because StickyFingers seems to be new to the hobby. I don’t think the advice “Leave to dry (usually an hour or so is good for careful handling, but overnight for full curing).” is good advice. I typically wait maybe a minute before handling freshly cemented parts, a little more if it is a delicate assembly, but never, ever for an hour or overnight. Taken literally, that would mean, for example, gluing two halves of a wing together, waiting an hour (or overnight), and gluing a flap on. That is not a realistic or needed delay. The solvent evaporates extremely quickly and the plastic of the two pieces essentially “dries” together into a new single piece in just a minute or less.
Tamiya Extra Thin (TET) is made for places where two parts are placed together with a tight fit, then it is applied to the joint. Applying to one part then assembling doesn’t work well because the TET evaporates too quickly. (Applying more isn’t a solution.) This is why you are finding that parts are loose.
You want a slower acting, less volatile cement for applying before assembly. I use Testors Liquid. I don’t know what equivalent products are out there. You don’t want a thicker, syrupy cement, just a liquid that isn’t as volatile. (The market seems to drive companies to make either “hotter” and hotter, quickly evaporating types or slow thick cements, but nothing in the middle.)
The other thing to do is yank that floor mop of a brush out of the bottle cap. It practically guarantees that you will be applying too much cement. Instead, get a cheap 00 or 000 brush and use it for cement application.
I think you’ll find that using a small brush to apply a slower-setting cement will give you the results you desire.
There’s a good example of this on a recent build posted here. When the cement actually melts the windshield frame, you may have used too much.
I’ll play nicely today and not link to it.
Bear in mind there are two flavours of Tamiya Extra Thin. the one with the darker green cap is a slower cement, and puddles of it on the surface will cause problems as you described. It can be flowed into a joint once parts are held together, but it can also be used as a dab where a small part is about to be placed. It dries slow enough to give a few moments to then press the part into place. I use it for adding tiny details onto larger parts, such as the headlights or lifting hooks onto a tank hull.
The other one is the Extra Thin Quick Set, with the lighter green cap. It dries very fast, and really needs to be applied to the joint once the parts are pressed together - it then wicks its way into the joint through capillary action. I find this stuff dries so fast that overspill rarely leaves any mark on the plastic surfaces.
But either way, it’s always best to be neat with the glue. It’s easier to keep surfaces clean than it is to sand them all afterwards!
Both are too fast for cement-then-assemble (as a rule), because they aren’t intended for that:
Tamiya EXTRA THIN model cement is used to glue together plastic model kits that use polystyrene plastic. No crevice is too small for this flowing adhesive, which was developed to flow into and stick the small spaces between two plastic parts which have been pre-fitted to one another. Furthermore, the extra thin formula allows the modeler to glue together small pieces that require pin point accuracy and finesse.
The Quick Setting Extra Thin Cement is the “quick setting” variant that dries around 4 times faster than the original Tamiya Extra Thin Cement, saving you time (and energy) holding parts in place! It also has less-tendency to seep out from part joints.
I think there are two reasons why you often see a lot of cement marks on models made by guys who use TET:
They are using it like it was much slower setting, putting it on a part then trying to assemble it. It often dries before sticking, so the remedy is, of course, to put on more cement!
I saw that demonstrated at my club meeting last week. It works, but I can’t imagine where I’d use it because I get clean joints using a small paint brush. For very small parts like bolt heads I use a different process altogether.
I suggest you watch a good build video or two on YouTube to see how really experienced modelers cement parts together. Right now on Nigel’s Modeling Bench Nigel is building a M24 Chaffee and watching him will greatly help you see best practices. He uses very tiny drops in key areas and lets capillary action fill in the area to be cemented. Then he may touch up with light brush in hidden areas. He is very good and his technique and demonstrations should help you.
Fair enough. I was thinking about joints that might be problematic and also trying to describe how the cement works (dissolving and drying). However, you’re correct that most joints are secure enough to continue with construction in just a few moments or minutes. So, a good catch and observation.
I would note, though, that the total time to dry depends on how much cement has been used and how large the joint is. If a fairly large amount of cement has been deliberately used, for example, to create some amount of “squeeze out” in order to fill the seam with dissolved plastic, the drying time could be as much as a day or two (a technique often used on two-part gun barrels or aircraft fuselages or ship hulls). If these kinds of joints are tooled too quickly, shrinkage forming visible “grooves” along seam is quite likely.
(If too much cement has been accidentally used, then the joint may be too soft to be self-supporting, with the parts not being able to hold themselves properly aligned until the solvent evaporates some amount. The time needed before such joints can be handled might be a few minutes, a few hours or even a day or more. In the meantime, they might also require some sort of clamping, taping or other external supporting until the joint has solidified enough to support itself or for further handling.)
Also, glue joints along parts that require clamping because those parts will not naturally align (warped, twisted, gaps, etc.) usually do benefit from or even require overnight drying.
I guess what StickyFingers really needs to know is that the gluing process is somewhat variable and requires a bit of judgement to assess how well things are going, and this judgement is formed with practice and experience. Understand what the cement is doing and how it works and incorporate some process into construction testing the efficacy of the glue to decide whether the parts need some time to cure or if the joint is strong enough to continue handling.
As in most things modeling there are numerous answers and many opinions, I have found both to be, for the most part, helpful.
So here are some of my opinions and answers.
I have found that Mr. Hobby Mr. Tool Cleaner works a well as Tamiya Extra Thin if not better and it is ~1/3 the price.
Tamiya makes a cement that is thicker and dries slower for when you have to futz with getting parts properly aligned, this is in the orange topped bottle. I normally use a toothpick for application but it does have a brush attached to the top.
Personally if I do get some cement outside the lines I will, after it sets, go over it with a very fine grit wet and dry, wet, sandpaper using a light touch. I really do not want to sand the plastic just lightly remove the cement. This is a practiced touch.
And don’t feel bad about when this happens, it is like something else that happens.
Thanks for the advice on larger joints or clamped joints. Being too quick to work on things before fully dried/cured actually is almost always part of my modelling issues. If you want you can make your own cement (and also air brush cleaner. I have read that Tamiya AB cleaner and Extra Thin Cement are same ).
From google:
“Standard Tamiya Extra Thin Cement is a roughly 50/50 blend of acetone and butyl acetate (or ethyl acetate).” and
“Quick-Setting version of Tamiya Extra Thin, the formula changes to a blend of about 40% ethyl acetate, 40% acetone, and 20% butanone (MEK)”
oh, and hardware store sometimes carry Ethyl Acetate but almost never Butyl Acetate, which you have to get from industrial chemical supply places.
All the model supply companies seem pretty good at re-packaging things and marking them up 500%
If you mean the stuff in the hexagonal bottle, that’s one of syrupy cements I was describing. “Syrupy” may be a bit of an exaggeration, but the fact that you can apply it with a toothpick indicates that it is thickened. You can’t do that with Testors Liquid or the other hotter cements.
If you are concerned about the cost of hobby brand products you are using far too much cement.
On a 1/35 scale tank model where I do some modifications, some armor texturing, and add a lot of details I might use a third of a bottle of Testors Liquid and maybe 1/8 of an inch of TET. I would say half of those amounts are lost to evaporation from open bottles, wiped off of the brush, and the puddles I use to stick small parts, rather than going on the model.
Testors and TET both cost about $6 a bottle, so I’m using less than $3 worth of cement per model. (Less than the price of a candy bar and bottle of Coke at a mini-mart.) For that small of an expense I see no point is screwing around with buying industrial chemicals, even if they were free.
