View Cart || Request a 2021 Catalog

Electron Microscopy Sciences

Technical Data Sheets

Aqua-Hold PAP Pen

EMS Catalog #71311


The Aqua-Hold Pap Pen is a special marking pen that provides a thin hydrophobic film-like barrier when a circle is drawn around the specimen. This barrier creates the proper surface tension to hold antibody solution or other valuable specimens within the target area on the slide.

The Aqua-Hold Pap Pen contains a special formulation that is water repellent and stable for a long period of time. The Aqua-Hold Pap Pen is used just like a paint pen to draw a well on a slide. After application the barrier material contained in the Aqua-Hold Pen is insoluble in alcohol and acetone, but can be removed after staining slide with xylene.

Aqua-Hold is-very effective for Immunostaining procedures by the Peroxidase-Antiperoxidase (PAP) method, ABC method, B-SA method, immunoflourescence method, ASD method, Enzyme method and Frozen Section method. The surface tension provided by the barrier ensures that only a small amount of antibody solution is needed.


Each Aqua-Hold Pap Pen contains 13 ml of long-lasting barrier material.


  • Do not use product beyond the expiration date.
  • Be sure to replace cap tightly after each use.
  • The solvent is flammable and possibly toxic.
  • Use the pen in a well ventilated area.


To start use of pen, take off cover and press felt tip down lightly on a glass slide several times on a flat surface until a flow of material is seen. It might be heavy in flow. If so, wait until the felt tip is fully saturated with film material (turns a darker brown) and wipe off the excess with paper towel. The Aqua-Hold is now primed and can be used to draw the desired barrier on the slide. Two specimens, separated by two circles, can be applied to the same microscope slide.


  • Store at room temperature (15° to 30°C).
  • Store tightly capped after each use.
  • Store away from heat or flames.

For Paraffin Sections

Deparaffinize and rehydrate the section according to accepted procedures. For proper adhesion of the barrier circle, the glass slide surface should be clean and dry. Remove the slide from water or buffer solution; dry around tissue section with water absorbent paper; encircle the section with the pen. Allow the circle to dry for approximately one minute at room temperature and return the slide to water or buffer. lf trypsinization or another proteolytic digestion is to be used, apply the film barrier after that step is completed.

For Frozen Sections

The film circle may be applied on the glass surface (at room temperature) either before fixation or prior to the first immersion in the water or buffer. lf the slide is treated with hydrophile, soak the slide in 0.1N hydrochloric acid for 30 seconds. Wash it with water and dry. This will help prevent the film guard from lifting.

Expected Results

When an Aqua-Hold Pap Pen is used to make a well on a microscope slide, and antibody liquid is applied on to the well, it should stay in the well.

Quality Control

The Aqua-Held Pen should be quality controlled for each lot received. To perform quality control, draw a I cm well on microscope slide and fully add 0.5 ml of water. Water should not overflow well.


  • The Aqua-Hold pen may need further priming after sitting without use. Refer to instructions for use above to continue using the pen.
  • Do not use Aqua Hold Pap Pen on wet slides.

Online Ordering

Aqua-Hold PAP Pen