Hi All,
I've switched to using prolong diamond and VALAP as a sealant for my coverslips (from using vectashield and nail polish) but I've discovered it's quite tricky to apply VALAP without making a pretty thick rim around the coverslips (I use 12 mm). My current method is to use a p200 and suck up about 70 uL VALAP which I then add drop-wise in a ring around the edge. I've tried using a paintbrush as well but the VALAP tends to harden too quickly.
Any thoughts?
why dont you try applying the Valap with a syringe, Although I am not sure if the plastic of the syringe will react with the Valap
A caveat -- if you want to use oil immersion with a 12 mm coverslip, there is no way to make a thin enough rim. You risk getting the valap on the objective lens -- very hard to remove. (don't ask me how I know!) For oil immersion you should use a larger coverslip or a hard-set mounting medium like Prolong Diamond or Vectashield Hard Set.
That said, for a neat application of Valap I wick away excess mounting medium beforehand with Kimwipe or filter paper. Use a metal spatula gently warmed in a Bunsen burner flame. Pick up a small amount of Valap on the spatula and warm it over the flame just until melted, then angle the spatula so that there is a small bead of melted Valap and just touch it to the interface of coverslip and slide. If there is enough Valap in the drop, slowly drag it along the edge of the coverslip. It will take several applications to get all the way around.
Thanks for all of the suggestions everyone! I'm going to guess the issue was that I wasn't preheating my paintbrush.
I'll try applying it with a warmed needle vs. a pipette brush vs. a pipette tip vs. a metal spatula and update on the results. If it hardens too quickly, I'll try adjusting the percent paraffin or try order a lower melting point paraffin.
Thanks Theresa for the warning! I'm currently not imaging my slides with an oil (or water) immersion lens, but I'll keep that in mind in case I need higher mag down the line... Using a larger coverslip isn't an option due to my electrophysiology rig being configured to mount 12 mm coverslips, but I'm already using prolong diamond so I'll just note to not seal those slides to avoid any mishaps.
Michael
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