by Nick Gromicko, CMI®
Tape sampling is the most common technique used to test surfaces for mold during a mold inspection. It provides valuable information. The species of mold, the relative degree of contamination, and the potential for airborne spore production may all be determined by tape sampling.
This method can be performed using either standard, clear cellophane tape or a packaged kit specifically designed for mold sampling. Both types involve sampling by direct contact to visible mold. The tape or a slide prepared with adhesive is pressed against a moldy surface in order to collect the sample, which is then sent to a laboratory for analysis. This method is non-invasive and will not damage materials or surfaces, when performed properly. Depending on the material, tape samples can be obtained from the surfaces of valuable furnishings and materials of historical provenance that have visible fungal growth, usually without risk of damage.
InterNACHI inspectors who perform mold inspections may already be familiar with this common method of data collection. All inspectors can benefit from knowing more about its advantages and limitations, as well as some situations where it may be best to avoid sampling.
Pros and Cons
There are some important factors to be aware of when deciding whether tape sampling is the most effective method for testing for the presence of mold.
- Tape sampling is quick and easy.
- It is inexpensive.
- It requires no set-up time.
- It requires no complex equipment.
- Many samples can be collected in a short period of time.
- Samples showing hyphae fragments and reproductive structures can provide proof of mold growth.
- Tape sampling allows for the quick identification of genera and species by a laboratory.
- Tape samples provide more data than air samples.
- Tape sampling is usually non-destructive.
- While tape sampling is an excellent way to collect samples where mold is easy to see, light-colored and highly airborne genera, such as Aspergillus and Penicillium, may not be as obvious and can be missed using only tape sampling.
- Some smaller, airborne mold spores do not readily settle onto flat surfaces, so tape samples may not accurately represent their presence.
- If a tape sample is collected from dust rather than an area of actively growing mold, or if the sample is taken at the most spore-packed part of a growth area, it is possible that only spores will be collected. This can make determination of the species more difficult.
- Using tape of any kind on certain types of materials, such as paper and varnished wood, may damage the item.
- Tape sampling is meant to be used for qualitative rather than quantitative analysis. Tape sampling can aid in the identification of mold, but cannot accurately determine the scope and severity of the mold problem.
The Bio-Tape™ System
The Bio-Tape™ system is one of the most popular tape sampling and collection products on the market. It consists of a flexible, plastic microscope slide with an adhesive area. The slides come packed in their own individual mailers and are provided with unique serial numbers for traceability and documentation.
Some benefits include:
- sample consistency and uniformity. The sample area is always the same and the center point is clearly marked;
- the samples are easier to handle than standard, household or office-use tape;
- each sampling device is identified by an individual serial number for documentation;
- low to no risk of cross-contamination because each sample is stored in its own mailer;
- the mailers provided protect samples during their trip to the testing laboratory; and
- samples are compatible with both optical microscopes and scanning electron microscopes (SEMs).
Here are the steps for collecting a tape sample using a prepared sampling kit, such as the Bio-Tape™ system:
- Remove the slide from the mailer and packaging.
- Be sure to record the sample number and all other identification information before taking the sample.
- Peel the protective liner from the slide to expose the adhesive.
- Place the sticky side of the slide on the area being sampled.
- Gently press the slide down to make contact. Excessive pressure is not necessary.
- Lift the slide off the surface and put it back in the slide mailer. Do not replace the protective liner.
- Record all the information for the chain-of-custody document, including the property’s address, the date and time of the testing, and the sample number.
- Mail the mold sample off to the laboratory for analysis.
Where and When to Sample
The use of personal protective equipment is recommended, including gloves and a respirator rated at N-95 or higher, because tape sampling requires direct contact and disturbance of mold-contaminated areas.
Tape samples may be taken when non-invasive, visual inspection reveals any of the following:
- moisture intrusion;
- water damage;
- visible mold growth;
- musty odors; and/or
- conditions conducive to mold growth.
Samples can be taken in each room or area where there is apparent mold growth. If there appear to be different types of mold present, as evidenced by different colors, for instance, each can be sampled separately. Visible mold on different substrates and building materials may also be sampled separately, with a tape sample taken from the mold on each material.
When Not to Sample
According to InterNACHI’s Mold Inspection course, do not take a mold sample if:
- a resident of the house is under a physician’s care;
- there is litigation in progress related to mold on the premises;
- it is a commercial or public building; or
- the health or safety of the inspector could be compromised by obtaining the sample.
Knowing more about tape sampling for mold inspections is beneficial because tape sampling is the most common data-collection tool used. Inspectors who are familiar with the details of this process will be able to utilize it most effectively when gathering data for apparent mold problems.