Introduction: Pressurized Filter

About: I enjoy hiking and plant foraging... but most of time I do chores!

You can use a coffee filter and a funnel for many kinds of filtration tasks, other than just coffee. What do you do when gravity takes its sweet time with the fluid you're filtering, or have something that's really viscous like deep frying oil? Well... use a pressured filter.

This instructable takes a very short time to complete and doesn't require much in the way of materials. Chances are, most materials are on hand.

Step 1: Gather Materials

You will need the following materials:
  • Coffee Filter
  • Acetone & Cloth
  • Ball Inflation Needle
  • Ball Inflation Pump
  • Sharp Utility Knife
  • Permanent Marker
  • High Density Polyethylene (HDPE) Container with Lid
  • Pencil
  • Hard Surface
  • Shaggy Surface

Step 2:

In this step, cut the hole for the filter.
  1. Place the lid on a shaggy surface, such as a carpet. You should be able to rotate it freely without it moving off its axis.
  2. Hold a permanent marker to the inner edge of the lid and rotate it to make the outline of the circle to be cut.
  3. Cut the circle with a sharp utility knife. Don't press too hard or the plastic may crack. You may want to predrill the lid, or use a Dremel routing bit instead.
  4. Use acetone to wash off any residual markings left by the permanent marker.

Step 3: Cut Filter

In this step, cut the coffee filter to size.
  1. Flatten the filter and fold it in half as many times as possible so that only 1 lid can be traced.
  2. Trace the lid at the very top corner of the folded sheet with pencil and cut.
  3. Unfold the sheet. Try to trace the lid again at the very top corner and cut if able to do so.
  4. Unfold the sheet. Again, try tracing and cutting.
  5. ...
With my container, I was able to trace / cut the filter paper 3 times. I folded it twice. The trace / cut yielded 4, 2, and 1 sheet respectively for a total of 7 filters.

Step 4: Assembly & Use

In this step, the filter is assembled and used.
  1. Using the tip of the utility knife, rotate a very small puncture into the center of the filtering container.
  2. Push in the ball inflation needle.
  3. Put a filter into the cap such that it touches each edge of the lid when inserted.
  4. Fill the container half-way (below the needle) with fluid needing filtering.
  5. Cap the container with the filter-lid.
  6. Invert the filter over a capturing container.
  7. Apply pressure to the ball inflation needle.
As pictured, I was filtering vegetable oil that I had earlier used to prepare some breaded talapia in a deep fryer. By itself, the quantity filtered would have taken over 4 minutes to penetrate through the filter. With pressure, it took about 10 seconds. Surprisingly, I didn't need to use a lot of pressure.