Resin and photo-etched BASICS

[ghodges]

A buddy emailed me with this question, and after replying, realized their are probably others who (as we old glue-smeared vets tend to forget) are just starting to use these things. So, I thought I'd share these, all of which are subject to addendums, modifications, and refinement! Hope this helps someone!

You're about to open Pandora's box! It's a wonderful world that can allow you to build more detailed and accurate models at the expense of time, money, and happiness!

But, the good news is YOU are in control as to how wide you open that box and how deep you delve into it. You don't have to add all of them at any one time; but can start small and use and add more resin and pe parts with time and experience. It's all up to you! Just realize that you're adding more steps, more work, and sometimes more frustration that you haven't had to deal with before. But, if your goal is to build a more detailed and accurate model, and THAT is what will make you happier and prouder in your hobby, then aftermarket can be a God send! Not trying to be negative nor keep you from using aftermarket. Just want to be sure you have an understanding of what to truly expect.

RESIN:
1) Must be glued together and onto a model with either super glue, Gorilla glue, or epoxy. Modeling (styrene) cements will not work.

2) Most model paints can be applied with no problems just like on plastic. BUT, occasionally resin parts will have a mold release residue on them that might keep paint from adhering properly. It's a good idea to simply scrub the parts with a toothbrush in a bowl of soapy warm water, as you might also do with plastic kit parts (for the same reason). Rinse and let air dry and they should be ready to go. Priming can help, but isn't necessarily needed.

3) Large resin parts may have a casting block still attached. It's usually best to use a saw to remove it, depending on how thick the block is. Resin is more brittle, so do NOT try to bend or flex a resin part from it's block or tree!

4) Warped resin parts can be heated in a pot of very hot (just before boiling) water and bent back to shape. Very thin parts can be heated with a heat gun or even a good hair dryer and straightened out.

5) Don't be surprised if a resin part is not a "drop fit", but instead needs trimming of it (or the kit) for a good fit. Resin shrinks during curing at a variable rate that even the manufacturers cannot completely judge or control, so expect to have to "work" to get interior parts to fit well and exterior parts to match adjoining surfaces perfectly.

6) Resin parts may have "air bubbles", small pits, or other surface imperfections. These can be filled and sanded like plastic parts. BUT, sand more carefully as excessive sanding can expose air pockets just below the surface, requiring more filling and sanding, which can expose more....ya get the idea!

Photo-Etch (PE):
1) Most of these parts come on trees (like kit parts) that require the part be cut off of. You can use a set of nippers or a sharp blade on a hard surface to do this. Until you get the knack (and even after), I suggest you get a big, 1 gallon, clear plastic baggie to use when removing parts. Put the entire tree into the baggie, insert hand with cutting tool inside and remove the part. Being INSIDE the bag means that if (and when) the part flies off it stays in the bag instead of launching itself into oblivion! An alternative (if using a blade) is to place the tree on some tape (sticky side up) so the freed part stays stuck on after it's freed from the tree. If you get pe parts that are individually etched (no tree) onto a rubber backing, these can be GENTLY peeled off, or soaked loose using lacquer thinner.

2) You'll need AT LEAST a metal straight edge and some needle nose pliers to bend parts. The simplest method is to put the part into the pliers at the proper junction and bend in the direction needed, provided that allows the space needed for the bend. The other most common method is to put the part under the edge of the metal ruler and then use a fine blade to get under and lift the part's edge to make the bend. The "length" of the bend (and common sense) will help you decide which method will be easiest and surest. There are some nifty "bending tools" available. Time and experience will tell you if you need one, but in general, if you end up using a LOT of pe (like on a ship model), the handier a bending tool will be!

3) Metal PE parts have "memory". When you bend or roll a part it will flex back a little leaving less than the desired result. To help lessen this you can "anneal" (heat) the parts tree. Simply place the tree on a stove burner until it turns bluish-red and then remove it and let it cool. The parts can now be worked easier with less "spring"; BUT they will also be weaker. Repeated bending back and forth of an annealed part can break it at the bend. I only anneal parts when they need to be rolled, as you can slightly over bend an un-annealed part to get the desired angle in the end.

4) Rolling pe parts is more difficult, but it allows you to make perforated gun barrels and mufflers! You need a "mandrill" (hard tube or rod) of a slightly smaller diameter than your desired finished part and a very deep, soft, padded surface. The mandrill can be a brass tube, knife handle, paint brush handle, a steel model car axle, or even a mini drill bit, depending on the desired diameter of the finished part. Whatever works, works! The "pad" is easily made by simply folding over a couple of sheets of paper towel until it's about 1/4" to 1/2" thick. You place the mandrill on the part and start to roll it back and forth so the part curls the way you want it to. BUT, USE VERY LIGHT PRESSURE TO START! If you press too hard, it can kink the part before it starts to curl. More pressure as you roll tightens the curl until it closes in on itself. This takes practice, and is much harder than bending parts to shape, but it can make for some realistic parts unobtainable in other ways (at least until 3D printing takes over!).

5) PE parts can be glued with almost anything except styrene cement. If it's bearing no weight (ornamental) then white glue, super glue, or even a drop of Future will do the trick. Parts that may have some stress or could be subject to knocking off during handling are better applied with gel superglue or epoxy. The real trick to gluing pe parts is using a small enough amount of glue so there's no visible glue mark!

6) PE parts can be painted like regular plastic parts, though they may be more prone to flaking IF you paint first and then bend. They may also have some chemical residue that might need washing away. Priming them isn't needed, but not a bad idea if you want better paint adhesion. Pre-painted (printed) colored PE parts are da BOMB! Ya just cannot paint the fine details they can put onto an instrument panel!

Please feel free to add what I've left out, or modify what is too simplistic! Cheers!

 

GIL

Edited January 25, 2015 by ghodges

[JohnRatzenberger]

Good stuff Gil.

 

Resin.

-- The Hasegawa Try-tool saws and the CMK saws are great for cutting pour blocks.

-- Do not try to cut with a knife blade -- although it really depends on the manufacturer of the kit/part and how they attach parts to pour blocks; I can probably cut 80% of a Resicast kit with a simple score using a sharp #11 blade because of the way they do their parts, others not so.

 

Photo-etch.

-- I bend most my small parts against my thumbnail using appropriate tweezers or pliers to hold the parts (not the thumb).

-- I use a single-edge razor blade as a bending tool, fits under most everything.

[Mark Aldrich]

And the Murphy add on for PE.

 

Unless you are GOOD, work with photoetch over a white sheet of paper! I usually use a piece of the Uhaul packing paper. For some unexplained reason, a flat piece of PE will act as if it were spring loaded while you are attempting cleanup.

[Guest PetrolGator]

Resin:

 

I use a flat sanding surface on pieces cast into wafers (like superstructure piece on a ship) where one has to remove resin from the bottom of a relatively flat piece. Simply and slowly sand the bit in circular motions, avoiding a lot of pressure. You don't want to end up oversanding one side and neglecting another. MANY small ships are cast like this. It's a pain.

 

I use Bleche White to clean -all- resin parts (and PE.) Paint is easily applied, though I still regularly prime.

 

It cannot be overstated: sand very, very slowly.

 

Warped parts are easily corrected in a warm water bath, but be mindful of the temperature. Always test your bath with a piece of junk resin from the kit.

 

PE:

I use those self healing rubber mats from Hobby Lobby. They generally tend to absorb some energy when the PE part breaks its bond from the fret, minimizing their aerial capability.

 

ALWAYS pre-paint your PE on the fret, or at least prime it. The resulting product is almost always neater.

 

Again, always clean PE before painting. Brake cleaner almost universally works (plugging Bleche White again here.)

 

Regarding PE railing, cut it into smaller and more manageable section. Join the severed bits with white glue or Gator glue. The residue tends to disappear and you'll rarely know where you originally cut the run.

 

 

....off the top of my head.

[JohnRatzenberger]

Resin:

 

I use a flat sanding surface on pieces cast into wafers (like superstructure piece on a ship) where one has to remove resin from the bottom of a relatively flat piece. Simply and slowly sand the bit in circular motions, avoiding a lot of pressure. You don't want to end up oversanding one side and neglecting another. MANY small ships are cast like this. It's a pain.

 

 

Good tip! I do a figure-8 - it places one side leading as you go down the 8, then the other side as you go back. Every 2 or 3 cycles, I rotate the part 90-degrees. I get (more or less) equal sanding and pressure and end up with a pretty flat bottom (the part, not mine).