Vaseline Syringes

Recipes

***Tweak the ratio of mineral oil to Vaseline for desired consistency. Lower ratios will be harder to push out of the syringe (will take longer to melt at high temperatures) and higher ratios will be easier (melt easier at higher temperatures).***

Calculated the masses using densities:

• • Density of Vaseline = 0.865 g/mL

  • Density of Mineral Oil = 0.838 g/mL):

10% Vaseline Syringe:

• • • 52 g Vaseline

    • 6 g mineral oil

      • Note: same as 45 mL liquified Vaseline & 5 mL mineral oil

15% Vaseline Syringe:

• • • 49 g Vaseline

    • 9 g mineral oil

      • Note: same as 42.5 mL liquified Vaseline & 7.5 mL mineral oil

Yield: approximately a dozen 10-mL syringes filled halfway.

Procedure

1. 1. Weigh solid Vaseline in a 100-mL beaker.

   2. Tare the balance and carefully add mineral oil with a transfer pipet, taking care not to overshoot your target mass of mineral oil.

   3. Set the beaker on a hot plate at 170℃ and stir with a spatula.

   4. Label syringes with label tape indicating the volumetric percentage of mineral oil in your recipe.

   5. Monitor the progress of melting Vaseline. If necessary, use a spatula to push solid Vaseline to the bottom of the beaker, taking care to scrape as much Vaseline off of the spatula back into the beaker when done.

   6. When the mixture is completely liquefied, stir for 20-30 seconds to ensure thorough mixing of the components. Let the mixture rest until there are no air bubbles visible.

   7. Submerge the tip of a 10-mL syringe with a needle attached into the Vaseline mixture WHILE STILL ON THE HOTPLATE AT 170℃. Very, very slowly pull up on the plunger to fill the syringe. The goal is to minimize the introduction of air bubbles, thus steady your hand at this stage and until you set the syringe down. It is critical to minimize any unnecessary jerking movements which will create many tiny air bubbles.

      1. • Do not fill the syringe with more than 6 mL of liquid (anywhere between 4-6 mL is ideal).

         • Once the syringe is filled, keep the tip submerged for 3 seconds before carefully removing it from the beaker.

   8. Very carefully reorient the syringe so the tip faces the ceiling. Push the plunger up to push out any air bubbles but avoid expelling any Vaseline. 

   9. Blot the tip of the syringe with a Kimwipe to mop up any escaped Vaseline which will solidify into a mess. 

   10. Put the syringe vertically into a bucket of ice to cool down.

   11. Repeat with the remaining Vaseline mixture and syringes. Stop once it is impossible to draw up Vaseline without introducing a ton of air bubbles.

       1. • Syringes with lots of micro air bubbles will be unusable, so it is better to discard any remaining mixture than to prepare a useless syringe.

   12. Once the syringes have cooled down and solidified place them into the container on the dissection bench.

Making Custom Tips for the Syringes