Home / Construction / Techniques / Working with Resin Parts

Working with Resin Parts

Accurate Armour Jackal Resin is associated with conversion kits, but is also used to produce complete model kits.  This allows the modeller to produce subjects that are not available from the larger kit manufacturers.  This is the excellent 1/35th Jackal from Accurate Armour.

Introduction

The vast majority of scale model kits made today are made from plastic (polystyrene).  Most modellers will, sooner or later, come acoss other materials and cast polyethylene resin is one of these.  Working with polyethylene resin requires different methods and products.  This tutorial is a guide to dealing with this material.

Background information about cast resin can be found in the article ‘Model Kit Materials’ and so we will not repeat it here.

Preparing Parts

Whether you are building a complete resin kit, or using an aftermarket kit to convert a standard plastic kit, you will find that the resin parts are likely to need more work on them than the more normal injection molded plastic parts that you may be used to.

Resin wheels Here are some resin wheels from a conversion kit made by Voyager.  Note how that are attached to a large casting block. The attachment points are much thicker than would be the case for injection moulded plastic and removing the parts can be quite a chore.

The quality of plastic kits on the market is very good and most modellers have become used to snipping a plastic part from the sprue and, with little or no clean-up, putting it on the model.  Unfortunately that will not be the case with resin.

Razor saws Razor saws are indispensible when working with resin parts. They come in different depths and can be used with or without a handle.

Resin parts are cast from a liquid and may well come still attached to the casting block.  If this is so, then they need to be separated. If the attachment point is thin then it might be separated with repeated passes from a sharp hobby knife.  However, if the attachment point is thick it will need to be cut off with a fine saw, sometimes called a razor saw, which is designed for hobbyists.  Normal saws available from hardware stores cannot be used as the teeth of the saw will be too large. The sawing process can be difficult and time-comsuming, especially if the link between the part and the casting block is large, but there is no way to avoid it.  You may wish to try using a motor tool to speed up the process, but great care is needed when doing this.  If too much friction is generated, the resin may melt.

The greatest difficulty can be cutting away the casting block without damaging the part.  Sometimes it is better to cut away the bulk of the casting block, leaving a small amount behind that can be trimmed away with a modelling knife.

Resin jerry cans Here are some resin jerry cans from the same Voyager set as the wheels above.  The cans are well molded and highly detailed, but it is necessary to carefully cut away the attachment that runs the full length of one side.

Note that whenever cutting resin like this, or sanding it, there will be a fine dust produced which is very bad for the lungs.  Wear a filter mask and clean up your work area afterwards.

When the parts have been removed from the casting blocks, they need to be cleaned up.  Any remaining lug where the part was attached to the casting block will need to be cut away with a knife or sanded/filed away.  There is also likely to be a seam that will need to be removed with a sharp blade.

Examining All Parts

Once the parts have been removed from the casting blocks and cleaned up they need to be examined.

Resin crates Here are some resin crates from a diorama set by Accurate Armour.  The detailing is superb showing a fine grain on the wood and miniature clasps.  The casting block is attached along one corner of the crates to make it easier to remove.

One potential fault is warping.  Check whether the part has become distorted.  For example, if it is the chasis of a vehicle place it on a flat surface and see if it sits right or whether it rocks back and forth.  If you find a part has been warped then it is possible to sometimes undo the damage by applying gently heat, such as boiling water or even a hair dryer which softens the resin and makes it possible to reshape it.  Clearly care needs to be used when applying heat in this way to avoid injury.

A second fault is air bubbles.  Sometimes tiny air bubbles can be trapped in the mould whilst the resin is setting and this might mar the surface detail.  These tiny holes are sometimes called ‘pin holes’.  This fault can be rectified with filler and sanding.  Remember that fillers designed for styrene plastic will not adhere to resin.  However, if the pin holes are tiny, almost any type of filler will work well.

Another thing to check for is the need to drill any holes.  Injection molded parts will probably have holes molded into them, but it is more difficult to create holes that go right through a part when it is cast.  It may be that the resin part has an indentation to show where a hole should be, so that the modeller can drill it out completely.

Gluing Parts

Superglue Superglues come in a variety of thicknesses.  Also available are activators to speed-up setting time and debonders for when you inevitably stick your fingers together.

Standard polystyrene cement which is perfect for conventional styrene models is absolutely useless for resin parts.  Poly cement works by slightly dissoving the styrene plastic, but it wll not dissolve resin and so will not work at all.  When gluing resin parts to each other, or to plastic, you will need to use either two-part epoxy glue or cyano (superglue) adhesive.  Both of these work well, so it is down to individual preference.

Epoxy Glue Epoxy cement comes in two parts, the adhesive and hardener.  They are usually mixed in equal parts.  Drying time varies depending on the type and can be anywhere from 30 seconds to 24 hours.

Cyano is the most convenient because it does not have to be mixed and so is probably the first choice for many modellers.  However, the epoxy cement will probably produce the strongest and most reliable bond.

Whichever glue you use, it will only work if the surface is prepared properly.  Both types of glue need a dust-free and grease-free surface, so wash the parts in warm water with detergent and dry them thoroughly.  The bond will probably be stronger if the surfaces to be joined are roughened slightly with sand paper.

Once you have glued the parts together, there may be a need for filler.  The normal fillers intended for polystyrene such as Squadron ‘Green Stuff’ and ‘White Stuff’ will not adhere to resin because they are designed to ‘melt’ the surface of polystyrene.  This does not mean that they cannot be used in certain situations, but you should be aware that they may flake away if spread thinly.  Epoxy putties such as Milliput, or other fillers that have a natural tackiness, should normally used in preference when filling resin parts.

Summary

Using resin parts does provide the modeller with additional challenges, but there are also additional rewards.  You have the opportunity to make an unusual or even unique model.  Using resin also gives you the opportunity to hone and develop your modelling skills.  Give it a go.  Try starting with a simple conversion kit to enhance or modify an injection molded kit and build up to a full resin kit.

GRAB YOUR FREE STEP-BY-STEP VIDEO GUIDE !Here you'll find the BEST on the web video tutorial on how to make 1:48 scale WW2 German jet. In our friendly step-by-step video guide we cover topics like: drybrushing, applying washes, applying decals and many more. Do not miss out - WE GUARANTEE THAT YOU WILL LEARN SOMETHING NEW!!!!New GraphicName: Email: We respect your email privacy

About Kris

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

Scroll To Top
GRAB YOUR FREE STEP-BY-STEP VIDEO GUIDE !Here you'll find the BEST on the web video tutorial on how to make 1:48 scale WW2 German jet. In our friendly step-by-step video guide we cover topics like: drybrushing, applying washes, applying decals and many more. Do not miss out - WE GUARANTEE THAT YOU WILL LEARN SOMETHING NEW!!!!New GraphicName: Email: We respect your email privacy