Canada Balsam Bottle

Quick Answer: The Canada Balsam Bottle is a small glass bottle for storing Canada balsam, the resin mountant used to seal coverslips on permanent microscope slides. A Canada balsam bottle keeps the balsam free of dust and slows the loss of solvent, so it stays at a usable thickness.

Canada Balsam and Permanent Slides

Canada balsam is a natural resin from the balsam fir, dissolved in xylene for use as a mounting medium. Its refractive index is close to that of glass, so stained tissue mounted in it looks clear under the microscope. In the classic method, a stained section is dehydrated through increasing strengths of alcohol, cleared in xylene, and a drop of balsam is placed on it before the coverslip is lowered at an angle to push out air. As the solvent evaporates the balsam hardens, sealing the slide for years.

Balsam’s weakness is how easily it thickens. Left open, the solvent evaporates and the resin turns stiff and stringy, and any dust that falls in ends up on slides. A dedicated bottle solves both problems. Balsam bottles are commonly made with a cover or cap over the neck, and many carry a glass rod through the stopper so a drop can be lifted out and applied directly. The listing does not describe the design of this bottle, so check whether a rod and cap are included.

Synthetic mountants such as DPX have replaced balsam in many labs because they yellow less, but the same kind of bottle suits them. Finished slides can be compared with those in the prepared slides range; sections are often stained in a Coplin jar before mounting.

Using and Cleaning the Bottle

• Keep the Canada balsam bottle closed between uses so the solvent does not evaporate and dust stays out.
• If the balsam becomes too thick, thin it with a little xylene in a fume hood rather than warming it over a flame.
• Wipe the rod and neck with a xylene-dampened tissue before closing, so the stopper does not stick.
• Work with xylene-based mountants in a ventilated area, wearing gloves, and keep them away from flames.

Specifications

Applications

• Mounting stained plant and animal sections as permanent slides in college practicals
• Making whole mounts of small organisms and insect parts
• Holding DPX or other synthetic mountants at the slide-making bench
• Mounting thin sections of rocks and minerals in geology labs

Why Choose LabEquip

Botany, zoology and histology departments that still prepare their own permanent slides need a dedicated bottle at the mounting bench. LabEquip lists it in Biology Lab Products; ask about the design and size through the contact page.

Frequently Asked Questions

What is Canada balsam used for?

It is a natural resin mountant used to fix a coverslip over a stained specimen on a microscope slide. Its refractive index is close to glass, so it keeps the specimen clear and preserves the slide for years.

Why does balsam need its own bottle?

Balsam thickens quickly as its solvent evaporates and collects dust easily. A covered bottle with an applicator rod keeps it clean and fluid and lets you apply a single drop without spills.

How do I apply balsam when mounting a coverslip?

Place one drop on the cleared specimen, touch one edge of the coverslip to the slide and lower it slowly so the balsam spreads without trapping air bubbles.

What should I do if the balsam has become too thick?

Stir in a small amount of xylene until it flows again, working in a fume hood. Do not heat it over a flame, because the solvent is flammable.

Can the bottle be used for DPX?

Yes, it suits DPX and other resin mountants. Keep one bottle for each mountant, label it clearly and do not mix different media.

How do I clean the bottle?

Dissolve resin residues with a little xylene in a fume hood, then wash with detergent and water and dry fully before refilling. Dispose of solvent waste according to your laboratory’s rules.

Last Updated: September 2026