How to work with PE parts
Glueing and filling
The fact that the parts we want to work with are made of metal was already mentioned. Therefore the fact that you can’t use the glue and the putty you use when working with plastic should not surprise you. These agents, both putties and glues for plastic, are based on melting the surfaces of the parts before joining them but I suppose that you do not want melt brass in your living room. Therefore no putty for plastic and no more Revell Contacta. Let’s have a look at what I use.
There are three main agents:
1) A good super (cyanoacrylate) glue. I do not want to force you into buying anything particular so the choice is yours. However the quality matters and all the glues I use I buy from Loctite (www.loctiteproducts.com). I suppose that their products are available worldwide so you should not have any problem to obtain it. In fact I do not use just one glue but three different types at the moment:
1a) A standard liquid Loctite Super Glue for general purpose (they call it Loctite Super Attak over here but I am pretty sure that it is the same as Loctite Super Glue mentioned on their website),
1b) Loctite Power Easy (3g package) which gives you few more seconds before it hardens and that is essential for working with fine parts you need to stick somewhere and have few extra seconds for perfect alignment – the Raba lettering on the cab side walls for example
1c) Loctite 480 (www.loctitehf.com) which following the Loctite spec sheet: “is a rubber toughened adhesive with increased flexibility and peel strength along with enhanced resistance to shock”. Hey, that’s exactly the one you need for PE parts, isn’t it? It is great for both glueing and filling. It is not as brittle as the standard super glue and again gives you few more seconds for possible alignment corrections. It has one more positive feature that is not mentioned in the spec sheet. It is not clear but black. Therefore you can clearly see where the glue is during the filling and sanding process while the standard glue is clear and not so easily visible.
2) A glue remover. It is a liquid that melts super glues. Clear, black…any of them. It does not melt plastic however it melts all kinds of paints so be careful when working with this and do not use it on painted parts. Let me explain why this is so necessary to have. A glue is used for filling when working with PE parts very often. You also need to apply glue on very thin parts and you usually overdose on that. Well, that’s a standard situation and I do that too as once you do not apply enough glue, the final assembly will be very vulnerable due to brittle joints. I therefore apply more glue rather than less and later remove the excess glue with the Microbrush applicator (www.microbrush.com, go for Disposable Applicators, I use both Regular (green) and Superfine (white) size) using the removing liquid. Of course you can remove the glue by sanding too but how about all the tight areas and corners? No way! That’s why I use it. I use a local product so try and ask around for something similar. I saw a Loctite remover which was announced as gel. I do not know how does that work but the one I use is liquid.
3) A cyanoacrylate glue accelerator. An accelerator is a liquid that accelerates the glue hardening. I can imagine your questions: Why the hell should I use this when a super glue hardens in a few seconds? Well, yes it does when applied correctly in just a small amount. However when using a glue as both a filler and a glue you usually need to apply more than a small drop. It may take more than a few seconds to harden. It may take 10 or 20 minutes when using the black Loctite 840. Once working on a certain part I do not want to waste time like this and I therefore use an accelerator for hardening even a thin layer of glue applied in certain area. The one I use is in a spray can so it is very easy to apply. I spray the area with the glue applied and can immediately start with sanding.
You might like to ask me: Why don’t you use any epoxy? Well I do but usually not when working with etched parts. Why? Because the epoxy glue is hard to sand therefore you can’t use it for filling. You also can’t use other agents I already mentioned - the remover and accelerator.
So once again: a glue, a remover (possibly with the applicators) and an accelerator. That’s all you need and the fact is that you should have all of this for working with resin and other non plastic materials too so there is no tool with just one purpose. That is fair, isn’t it?
An important note: store you super glues in a fridge. This will help the glue to last longer as all the reactions resulting in hardening the glue inside the original package are much slower at lower temperatures. Put the glue into the fridge every time you don’t work with it. The hardening reaction is caused by the air moisture. Therefore always make sure the glue tube is closed and that the cap seals properly
Once you have all the items mentioned above you also have all I use when working with PE parts so we can move forward and start talking about the parts themselves. The main issues and questions connected with PE parts are the following:
- How to cut the part out of the fret or how to cut them in general (when working with general catwalk plates or radiator mesh for example)
- How to manipulate the tiny parts such as all the badges and lettering you can find in CTM sets
- How to bend the parts
- How to glue the parts together
- How to fill the parts when necessary
- How to paint the PE parts and especially how to paint the tricky bits and pieces
Some of these operations are rather standard and you just treat the PE part the same way as you treat the plastic one. Sometimes however a special or clever trick may be necessary to complete the task. Lets go through the operations mentioned above and see what they require.
As most of the PE parts are made of rather soft metals (brass especially) you should not have any problem to use standard scissors to cut the parts. When a straight cut is required (when cutting a tread plate for example) a metal ruler and a sharp knife can handle the task easily. Yes, you blunt the blade faster but there is no other option. I use the scissors for cutting the parts out of the fret however you can use a knife on a tough surface too.
It may happen that a piece of the “bridge” connecting the part with the fret will remain on the part where you do not want it. Use a fine file for removing it. It may be tricky to sand the bridges off on the tiny parts. Sometimes it is better to use the knife instead of scissors when cutting the parts out of the fret as it is more accurate and usually allows you to remove the complete bridge leaving no visible marks.
Always remember that the tiniest PE parts can easily fly away with just one breath out and easily disappear in the black hole under your table (together will the rest of the tiny parts, nuts, bolts and etc.). It is good to store all the parts you do not need sealed in a box to prevent losing them. Large parts such as mud flap or a radiator grille do not need any special care in terms of handling and manipulation. On the other hand there are many nice but fine parts such as all those small badges and letters that are barely visible. How should one pick them and fit into the right position on a model? Although there are many types and sizes of tweezers available, there is another way how to manipulate even the smallest part allowing you to apply glue on it and then stick it on the cab surface. Toothpicks are very helpful tool in truck modeling. I know many ways how to use them as a special handling tool is just one of them. All you need is a toothpick (There are many shapes used around the world however I prefer the sharp rounded ones. The sharper the tip is the more accurate tool you get. Then you will need Tack-it. Tack-it is (according to its manufacturer Faber-Castell) a multipurpose removable and reusable adhesive which can be used on a variety of surfaces including wood, metal, plastic paper. Hell, that’s all I build my models of! How can I use it?
Do you remember some pictures of my models in a mock-up state? Assembled prior to painting just to verify that all the parts fit correctly? Well, its Tack-it what holds the model together. No glue just a piece of green chewing gum which can be removed easily once you put the mock-up back into pieces and rolled to the ball to keep it ready for the next action.
Well, now when you roll a small ball of a few mm in diameter and stick it to the end of the toothpick, you get a tool which you can use for lifting up any small part from the mat. You can use it for PE parts or even the decals without any harm to them. You can pick up an etched part with this tool, use another toothpick to apply a small amount of glue to the contact area and stick the part into the correct position on the model easily. I can’t imagine any other way of applying the RÁBA lettering to the cab side walls.
Just to add all the information I should say that I use Tack-it from Faber Castell before I bought one pack about 12 years ago and it is big enough for the rest of my life but I think that there are other producers offering the same or similar thing giving it a different name (Kores Gumfix).
Using Tack-it for manipulation is fine but sometimes you need to secure the part better especially during spraying as it is quite easy to blow the part off the toothpick with an airbrush (again: blow off = fly away = black hole = lost forever).You might like to paint them with a brush but I don’t do that. I suppose that airbrush can give you finer coat of paint when working with tiny parts so how to secure them for spraying? Well, I use the Tamiya masking tape and I wrap it around something. I say something because it generally does not matter on that. I use a small piece of wood or an old metal ruler. The trick is that the sticky surface of the tap should point upwards and remain free. This is where you can now stick all the tiny flat bits such as lettering and different logos and badges. They are well secured now so you can use an airbrush to paint them. Easy and effective.
3) Bending and rolling the PE parts
As the etching technology allows working with plain flat sheets of limited thickness (mostly around 0.16-0.2 mm), all results are flat as paper. To make a three dimensional subject some bending operations are needed. Working with PE parts this way is very similar to building a paper model. All the parts are printed on a paper and it is up to modeler to give them their final shape. It is the same with etched parts however they are much more difficult to form as the brass properties are different to properties of paper. Still the basic principles remain the same. The parts can be bended and rolled and three dimensional objects can be created. As for the most common parts in truck modeling I would say that a standard 90 degree bend is the most common followed by similar operations resulting in 45 degree bends and etc. Rolling usually takes place when preparing the exhaust heatshields.
When bending paper you just use the ruler (you even do not need a metal one) to provide an edge along the bending operation is performed. The paper is soft and there is no problem but bending brass plate is something different. Therefore you always find a pre-etched line everywhere the bend operation should take place. Remember, this line should remain inside the corner once the bending operation is finished. It should form the inner edge and not an outer one. If you place the etched part and the etched line poins upwards, you should bend the flap upwards. This means that the position of the pre-etched line indicates not only the right place for bending but also a direction.
At a special occasion where some pattern or structure was applied over the parts surface the lines for bending may not be present because you only can etch through the half of the sheet’s thickness and adding a line over a pattern would simply get directly through the sheet providing a hole not just a gap.
Now, bending the part simply means forcing one half of the part towards a solid mat (eg. using a metal ruler on a cutting mat) while lifting up the second half of the part up from the mat with a knife blade which results in creating a bend along the edge of the ruler so that the ruler does not only provide the acting force which holds the part in place but also provides an edge that defines where the bending actually takes place. If you try to bend a part just in your hand, the result will probably be an irregular bend which may not follow a straight line and which has a large radius as there was no support edge for providing a sharp bend. The pre-etched lines usually help a lot so just a minor force is necessary for bending and a sharp edge is created easily.
Rolling the exhaust heat shields is the most common rolling operation on truck models. All you need for this is a pipe of an appropriate diameter – usually smaller than the final diameter of the heat shield because the part usually springs back a bit so you can’t use 12 mm pipe for reaching a 12 mm diameter. Starting from the flat PE part slowly start pressing the heat shield over the pipe and slowly wrap the etched part around it. It is useful to start with a pipe of a larger diameter at first, let’s say 20 or 30 mm to avoid any sharp bends or edges on the heat shield that are difficult to remove so a radius on the flat part can be generated slowly in small steps avoiding any problems.
OK now. The bending is over but you need to stick more parts together mostly. Usually you also need to stick a PE part to a plastic one. Well, all these cases can be easily handled by one of the super cyanoacrylate glues mentioned above. The final assembly is probably not as tough as a plastic assembly and the joints may be brittle but when you handle the parts with care you should have no problem.
There are two tips I would like to mention here: an application tool for super glue and a way of handling it.
How do you apply glue? Standard cements for plastic models are fitted either with a brush or a needle applicator which help with an application of a correct amount of glue exactly where you need it. But how super glue should be applied? Well, you can get it with a brush too but that’s not very suitable for a fine application and an applicator of most tubes usually does not enable a gentle application either. So how should one apply a small amount of glue on a V8 logo that is just 3 mm tall or an edge of a 0.16 mm metal plate?
Well, a friend of mine showed me his custom made and super detailed extra tool for a glue application. I made it myself too and I haven’t used anything else since then. I will share this secret with you. This highly evolved tool consists of a wooden stick (could be a toothpick of a skewer) and a thin metal stick (could be a steel wire or small diameter syringe needle). The wooden part forms a handle and the metal part glued into the handle is used to carry a small amount of glue. I machined a small flat area at the tip (I use a 1 mm syringe needle) which allows me to carry just the right amount of glue and place it anywhere I need. Of course, there will be more and more glue remaining on the tip of your tool. Use a lighter to remove it – all the remaining glue will burn and your tool will be clean and ready for use again.
I do not use the original package for the glue I work with. When working with the glue regularly, the applicator usually gets covered with remaining glue, opening and closing gets more difficult, the cover does not seal properly and the glue inside the tube hardens. The only thing you can do is to throw it away and get a new one. I will tell you how I do it.
I use a 2 ml medical syringe for a small amount of glue I work with. This means that every time I need glue, I fill a syringe with a small amount of glue (not more than 1 ml, usually just 0.5 ml is enough for many days or weeks) and put the rest in the original tube into the fridge. So now you are working with more than enough glue but you still keep most of the glue you bought in a fridge preventing it from hardening too soon. I use a cap from a syringe needle to close the syringe and prevent the glue from hardening. When properly closed the glue in the syringe lasts for many weeks. Once you run out of it, you can fill the syringe from the original tube again.
Now, if remove the cap and push the plunger gently a small drop of the glue will appear on the syringe tip. It needs a bit of practice to get just the right size of the drop. Once it’s too big, it will spill out or if you push the plunger too fast the glue will be blown out covering everything around so don’t try this on new leather sofa. However, you now do have the glue remover which can be used to sort most issues out. Use a piece of Tack-it mentioned before to ensure the syringe can stand upright on the table. Now it’s secured and you can use the tool created in the previous step for a precise glue application. Once your done just push the plunger back which will suck all the glue back in (make sure you don’t keep any air inside, just the glue) and you can put the cap back. The air moisture causes the glue hardening will cause even the glue in a properly sealed syringe will harden. It may take weeks but you can’t avoid it. Well, that’s the reason why you keep the original package in the fridge! Once the glue in the syringe cannot be used anymore, just throw it away, fill a new syringe with a small amount of glue again and go ahead. It is cheap and saves money. I have never thrown a super glue hardened in the original package since I started working with glue like this. I bought a 20 gram package of the Loctite 4 years ago. I was told that it may last for a year or two but I still have it in my fridge and still can work with it!
One more tip involves popular Tamiya masking tape. It may happen sometimes that you need to fix the part’s shape for glueing so that you do not need to secure the correct alignment with your hands all the time. Assembling our toolbox is a good example. Well, why don’t you use the Tamiya tape for that?
I have already mentioned that standard putty for plastic cannot be used when working with PE parts. However sometimes it is important to hide a joint and seal to obtain a smooth finish without gaps before painting. Well, as the super glue adheres to the metal surface much better than any putty you can use for such a fine work, there is no reason for not using it as filler too. Just apply enough glue in the gap, on the edge or simply anywhere you need it, apply the glue accelerator and remove the excess either with sanding or a glue remover mentioned before. There is nothing special about filling PE parts. Do it just the same way as you do when working with resin or plastic parts. The only difference may be the fact that the parts are usually small and fine and that the assembly is brittler than the one made of plastic.
Well, painting of PE parts does not represent anything special comparing to painting other parts. You should be careful when handling painted PE parts as the paint usually does not adhere to metal as good as to plastic or resin and any careless handling will probably damage the painted surface. I recommend using a primer before a final painting but you can use any paints you want. It will do no harm to the parts.
There are two special areas where painting of PE parts needs a different approach and that is painting of the smallest and finest parts and painting structured parts such as various plates or dashboard panels.
In fact all important features connected with painting the finest parts are mentioned above. The trick is not how to paint them (I always use an airbrush) but how to secure them before being blown away by the air flow from the airbrush. Well, use the Tamiya masking tape as described above and that’s it!
Painting of parts with various patterns and structures such as dashboard panels may not be so easy. You can use a brush and try and paint all the details by hand using this good old method. Congratulations if you can make it but I can’t so I do it a bit different way. First of all it is an advantage that there is a pattern on the surface. This allows you to spray the part with a fine black coat for example and then remove the paint from the raised areas of the surface structure by careful sanding using a very fine sanding paper or a sanding stick. Now you have a black background with all the raised details in the native metal surface. It is easy and very effective. Now you can paint the various buttons and switches using a fine brush.
Well, ok. That looks good but how about a TIR plate for example. You want it blue and white not blue and metal. How to do it? In case you want the elevated details in different color than the background is spray a coat of the one particular color over the part before applying the second color. This means that you will spray the TIR plate white prior to spraying it blue. Make sure that the white coat is a bit heavier and the blue very fine because you want to remove the blue from elevated area easily but you do not want to get through the white to uncover the original metal finish on the other hand. You can even use more different colors prior to the final one. When painting the 80km speed limit plate I used black for the lettering and red for the outer edge and then sprayed the whole part white. Working slowly with care the white coat was removed from the part showing red circle with black letter and numbers. The first attempt may not be successful but there is a big advantage here: you can always wash the part with thinner and start again.
The latest technology, of course, offers painting the part during production. This way the painted pattern may be extra fine and this allows many beautiful details on the dashboards especially. However this technology is still in development so it is not good for any application and still has it't limits.
Well and that’s it. Cutting, handling, bending and rolling, glueing, filling and painting was described so there is nothing else to be told about PE parts. It may seem to be easy however working with PE parts still needs some practice and experience. Such parts can be expensive and make sure you gain some experience with classic plastic parts prior to working with photo etched parts. However working with PE parts can be sometimes referred as tricky everyone should try and learn how to treat them as PE parts provide the finest and top level details any other production method is not able to offer and can bring many new and previously unseen details to the world of model trucks so that building model trucks can keep up with the worlds of model aircrafts of AFVs.