How to Rough Up Your Discs

Roughing up your discs provides extra grooves for the OCT to cling on to, hopefully preventing the OCT block from falling off when you're cutting sections. There are a few different types of discs that we work with:

Copper discs without holes: This type is excellent at gripping the OCT. Personally, I've never felt the need to rough these discs up, as they do a perfectly good job as they are. They DO, however, take more time to get cold.

Aluminum discs without holes: This type freezes quicker than the copper discs. The circular ridges seem to grip the OCT relatively well, but you might want to rough up the surface for added gripping power, just in case.

Aluminum discs with holes: These are the discs that give techs the most problems. I absolutely recommend roughing these up.



There are two ways to rough up a disc (plus one extra that I'll explain later but won't recommend):

Method #1 - Rub the surface of your disc against cement.  You'll probably find a suitable surface in a parking lot.

Method #2 - Use a screwdriver and your body weight.  This is my favorite method, since you can do it in the office and don't need to remember to do it on the way home. Place your disc ON A CARPETED FLOOR ONLY with your screwdriver at the center of the disc. Lean your body weight into it until the screwdriver slides down to the edge of the disc.  Turn the disc and repeat until you get several grooves radiating out from the center.

Method #3 - Garbage disposal. Obviously, I can't recommend putting your disc through a garbage disposal. I only discovered this method by accident. Ironically, it transformed a problem disc into one of the best discs I've ever worked with. Again, don't do this!

Making Slanted OCT Blocks

Why:  With some cryostats, you NEED to make slanted OCT blocks in order to line up.  (Note that I said “some.”  You never know which cryos require it.  It keeps things exciting.)

If you make a perfectly level block and try to line it up on one of said cryos, you’ll find that it's impossible to close the gap between the top of the block and the blade.  Your options at this point are:

1. Rotate the block upside down. You'll also have to pick up the sections with an upside-down slide so that piece 1 is still on the left side. Or,
2. Melt it down and remake it as a slanted block.

Since you never know which cryos require this, it’s best to just get into the habit of making slanted mounts every single time. 

How:  When sandwiching the tissue between the heat sink and the disc on the cold bar, angle the mounting slide so that the OCT block is thinner on the side closest to the cryostat wall.  It doesn’t need to be steeply slanted, just a subtle slant that you probably won’t be able to see until you take the frozen block off the cold bar.  

Be careful not to make the OCT block so thin on one side that it cuts directly into the disc.  You won’t be able to get any sections from it and you’ll have to melt it down and start over. 

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