How to Work With Resin Products?
Today, the scale model kit industry mostly revolves around plastic (polystyrene) parts and materials. Unfortunately, if you’re a hardcore modeler, then eventually you’ll stumble upon different materials like polyethylene resin. As you can guess, to work this type of resin, you’ll need completely new products and methods. This guide will help you understand how to approach this kind of material.
Resin can be used in a lot of different ways. To build up Complete resin kits from scratch or using conversion kits to remodel your plastic kit. But if you’re used to plastic parts and models, resin as a material will need more work to complete.
Plastic models are always simple to build since the quality of the kits on the market is usually very high. The only thing you have to do is cut the plastic part apart from the rest and smack it right on your model with nearly zero mess.
When working with resin parts, it might still be connected to the casting block when you first open the pack. If so, you need to separate them. Connection points can be thin or thick. Thin connections can be easily separated with a hobby knife. But if it's the latter, you need to cut it off with a razor saw designed for resin parts. Normal saws will ruin the resin part since the teeth are too big and too thick. The separation process might take some time depending on the thickness of the connection so you need to be patient. Using an electric tool might ease your job but you need to be careful if you generate too much friction, it could melt the resin. In general, it is very difficult to separate the block without any damage. That is why it is preferred you cut away only the majority of the block and sand or chip it away the rest slowly.
When the casting block is detached, the remaining imperfections on the parts also need to be trimmed, cut and, sanded away like lugs and seams.
Resin produces a lot of dust with processes like sanding and cutting. These specks of dust are extremely dangerous for your lungs so make sure to wear a filtering mask. Also, keep the mask on until your job is done and the working area is clean.
Inspect Every Part
Look for potential faults by examining every part, after they’ve been separated from the casting block and cleaned. Check for distorted or warped areas. You can use low heat sources like air dryers or boiling water to make the resin more malleable. That way you can reshape the part to fix the fault and undo the damage. When using heat, always be cautious not to hurt yourself or cause irreparable damage to the part.
Another type of imperfection is air bubbles. Trapped air bubbles in mold can distort the surface while the resin sets. These ‘pin-holes’ can be fixed by sanding or applying filler. Normally filler is created for plastic parts and cannot stick to resin, but if the holes are small enough, it will work no matter what.
The third fault is drill holes. Since it's hard to make holes that go right through when casting, the resin might have markings where the modeler needs to drill a hole themselves.
Putting Everything Together
Resin parts cannot adhere together with polystyrene cement which is used only for standard styrene models since it cannot dissolve the resin. But if you’re working with resin parts, only Cyanoacrylate or two-part epoxy will fill the bill. There is not much difference between the two, only personal preference.
Cyano is more practical since you can apply it immediately. Although you need to mix the epoxy cement, it forms the strongest bond between the two. Before you apply the adhesives be sure to clean your parts thoroughly. All the dust, grease and humidity needs to be wiped away. Use lukewarm water with detergent. Dry it off completely. Sand away the bonding surfaces and create rough textures to facilitate the bonding process.
Although resin is much challenging to use, the fine details of resin parts are always worth the time. It is also a very good practice material to better yourselves and improves your modeling skills. Start with some conversion kits and when you perfect the skill then you can move to more challenging kits.