The Problem with Resin Models

 

The Problems with Resin Models

As some of you know I've been in the resin casting business off and on for about 25 years. I've recently decided to get back into it under the new business Micro Reproductions. Technology advances all the time, and its no different with casting. New mold materials, more advanced resins, and better machines are making castings better all the time.

I thought I'd poll the Resin Railroad Modeler's Facebook Group and see what they thought were the biggest problems they are experiencing....

1. Warped parts. Nothing is more frustrating than getting a model, like that of a flat car, and the first thing you have to do is to warm the casting and flatten it out. Deformed one-piece car bodies are the worst problem.

2. Air bubbles in the casting. Usually this is mostly an appearance problem with the quality of the model, but it can occur in a problem place where a detail or critical part has to be mounted. Either way they have to be filled and sanded.

3. Poor quality castings. This is a cottage industry, and most castings are made by semi-pro mold builders in their basements. Nothing wrong with this but they don't usually use the proper resins, tools and methods to get the best products.

4. Difficulty Painting. Resins can have an oily finish if the wrong materials are used or release agents are put on the mold and not washed off. Acrylic paints can be difficult to apply, and chipping can result. One great cure for this is casting in color.

5. Poor fit. Resin casting usually contract, mostly around 4%. Getting things to fit accurately is a bit of an art. Some castings are reportedly 1/8th of an inch off! Designing and qualifying the part and mold are critical.

6. Drilling and fitting. Some models require the drilling of many holes for items such as grab irons and hand rails, instead of the hold being cast into the piece.

7. Fragile small parts. Resin parts are reasonably strong if thick enough, but small parts can be brittle and break easily. Changing the resin formula can sometimes fix this.

8. Poor directions. This is common to all types of model kits, not just resin ones. The vast majority of kit makers are not good instruction writers. It is recommended that they outsource this service. Often they don't make reference to the parts in the kit. The photos can be very poor quality as well. Super heavy text pages are very hard to model from.  

9. More difficult to build than other kits. Injection molded kits are far easier to build, I agree! But is that because the kit is resin, or because we are using resin to make up for getting a model, we need instead of spending big bucks on an injection mold tool? I do know this; resin models are far more fragile on the layout that plastic models.

10. Resin dust. Resin dust is extremely fine and gets everywhere. Some resin dust is toxic. 

11. Too much concentrated detail. Sometimes the detail on one area of a model is so dense that the components are hard to paint and weather. It also prevents customizing. Might be better if the detail was stackable instead of unit cast.

12. General assembly. Resin is difficult to glue together. CA adhesives are common, but the bond is brittle, unlike plastic cement that fused the parts together. I've even used screws to put large pieces together as resin drills and taps nicely. Epoxy is another method, but that has to be mixed in small amounts, stinks, and is messy to use.

Keith Wiseman of  Wiseman Model Service offers this help:

The best solution to your parts not falling apart is cleanliness of the resin castings before assembly. Before any assembly or painting you must thoroughly clean the parts in warm soapy water and rinse or a really good wipe down with Alcohol or similar solvent. Most all manufacturers use a mold release when making the parts and it stays on the model. Paint and glue do not stick well to mold releases. Same issue with Talc used when making white metal parts.

13. Not enough new kits coming out. The Covid issue has caused model railroading to explode with new modelers and a surge in building by current modelers. Getting kits is getting more difficult as well since the supply is dwindling due to demand.

14. Part numbering. It can be difficult for someone to figure out which part is which if they are not numbered or identified somehow. The instructions at least need to have clear pictures of the parts for identification. I prefer a page that is nothing but part identification.

Some of the good things about resin kits:

1. It can provide a way to get a model of something that doesn't generate enough interest to mass produce, such as a rail car from a shortline that no one but me has heard of.

2. It build your skill set. They are challenging. 

3. They are satisfying to build. Spending your hard earned dollar on kits, you want some fun back! They take time to build, and provide you with a creative outlet.

Other ideas for improvements:

1. DVD or video on line to show how to build the kit

2. Picture based guide instructions

3. Include techniques, tutoring, something extra to help advance the modeler's skills.

What bugs YOU about resin models?? Post your response below, or send me an email to scottgperry@comporium.net.