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Removing resin casting wafers by Don McKeand
Resin kits – dealing with parts on a “wafer”

When you get a resin kit, you will frequently find the superstructure and fittings cast on a “wafer” of resin, as well as waterline hulls such as the ones obtainable from Fine Waterline.
 
 The wafer can vary in thickness and removing the parts safely from it can be problematic.
 
My solution is to sand off the surplus resin. I favour using silicone carbide abrasive paper as it does not clog easily and comes in a variety of grades. Very thick wafers can be rapidly reduced with a coarse grade, and then finished with successively finer grades.
 
The problem is when to change to a finer grade, and how to remove just enough material while ending up with a level base.
 
If you have ever built a vac-formed model aircraft, you will be familiar with this technique.
 The first step is to use either a very fine pen or an extremely sharp pencil to make a line around all the components. Try to get as close into the edge as possible.  (photo 1)
This line is your indicator. Cut away as much of the surplus wafer as practical to avoid creating more dust than you have to. (photo 2) If there are a number of very small components to be removed it may be better to leave them together on the wafer as it gives you more to hold onto while sanding. If parts are large enough to be held comfortably then separating them makes sense.  
Small components with a flat top can be held on a piece of T shaped aluminium with double sided sellotape. (photos 3 and 4).  This can also sometimes work on such things as a group of upturned lifeboats, but anything sanded using this device needs to be fairly robust.  
The sanding is done with a sheet of abrasive clamped or taped to a flat surface, with the components rubbed on the abrasive. This process will create a fair bit of dust, so it can be an advantage to work outdoors. You should also use a dust mask as any type of dust in the lungs is bad news.
As you sand the components, keep checking on the thickness of the remaining wafer. If one side looks thicker than another it will indicate where to apply a little more pressure, but try to keep it as level as possible.
 
Once you can see the line through the resin it is time to change to a finer grade of abrasive.  (Left hand component in photo  5)
Keep sanding and checking frequently as the line becomes clearer and clearer and eventually the wafer will become so thin that it will fall away at a touch. (photo 6).  If you have removed material evenly you will end up with a component exactly the size the manufacturer intended and it should have a good flat base.