Spore Trap vs Tape Lift vs Bulk:
Which Mold Test Do You Need?
Most bad mold results are not lab errors — they come from the wrong sample. An air sample cannot tell you whether a stain is mold, and a tape lift cannot tell you what you are breathing. This guide compares the four sample types an accredited lab analyzes, so you collect the one that answers your question. For analysis, see our mold testing in Houston service.
The Four Mold Sample Types at a Glance
| Sample | What it collects | Best for | Report shows |
|---|---|---|---|
| Spore trap | Airborne spores from a measured air volume | Odors, complaints, indoor vs. outdoor comparison, clearance | Spores per m³ by genus |
| Tape lift | Spores and fungal growth on a smooth surface | Confirming a visible spot is mold | Presence and spore types, relative loading |
| Swab | Material from damp, rough or hard-to-reach surfaces | Textured walls, ducts, coils, drain pans | Presence and spore types, relative loading |
| Bulk | A small piece of the material itself | Water-damaged drywall, carpet, insulation, wood | Fungal growth and spore types in the material |
At AGT Labs all four are analyzed by direct microscopy under our AIHA EMLAP accreditation (LAP-101470) and Texas TDLR Mold Analysis Laboratory License LAB1070.
Spore Trap Air Sampling
A pump pulls a measured volume of air through a cassette — such as an Air-O-Cell — where spores impact on a sticky slide. A typical sample runs at 15 L/min for 5–10 minutes, for 75–150 liters total. The lab counts spores under the microscope and reports spores per cubic meter, by genus.
There is no federal limit for indoor mold spores. Results are read comparatively: indoor counts at or below an outdoor sample taken at the same time, with a similar mix of genera, generally point to no indoor source. Elevated indoor counts, or water-damage indicators such as Stachybotrys or Chaetomium indoors, point to an indoor problem.
Use spore traps when you smell mold but cannot see it, when occupants complain, and for clearance after remediation. Always collect an outdoor control.
Tape-Lift Sampling
A tape lift is the simplest mold sample: press clear tape onto the suspect area, then seal it on a slide or in a bag. Under the microscope the analyst can tell mold growth from dirt, soot or staining, and identify the spore types present.
- Strength: fast, inexpensive, and answers the question "is this spot mold?" directly.
- Limit: it describes only the spot you sampled — not the air, and not what is behind the wall.
Swab Sampling
Swabs do the same job as tape lifts on surfaces where tape will not lift cleanly: rough or textured walls, wet surfaces, and the inside of ducts, coils and drain pans. Swab the area, return the swab to its sealed tube, and label the location.
Bulk Sampling
A bulk sample is a piece of the material itself — about 2 × 2 inches of drywall, carpet pad, insulation or wood, sealed in a zip-top bag. It shows whether fungal growth is present in the material, which helps define what needs removal during remediation.
Combining Methods for a Complete Picture
Most investigations use more than one sample type:
- Visible spot, no odor elsewhere: tape lift or swab.
- Musty odor, nothing visible: spore traps indoors and outdoors, then surface samples where counts are highest.
- After a leak or flood: bulk samples of damaged materials plus surface samples of nearby areas.
- After remediation: spore traps inside and outside the work area plus surface samples, for your assessor's clearance determination.
Mistakes That Make Mold Results Useless
An indoor spore count without an outdoor comparison cannot be interpreted.
Too little air misses spores; too much overloads the slide. Follow the cassette maker's flow and time.
Air movers and tear-out stir up settled spores and inflate counts.
Skin cells and fibers obscure the slide.
Unlabeled or undocumented samples are hard to defend. Ship the same day or drop off in Houston.
AGT Labs is an analytical laboratory and does not collect samples on-site. Your assessor, contractor or you collect them; we analyze them at 10200 East Freeway, Suite 101, Houston TX 77029.
Mold Sampling Methods — Frequently Asked Questions
Which mold test is the most accurate?
Can a spore trap tell me where mold is growing?
Is a tape lift enough to confirm black mold?
Does AGT Labs analyze all four sample types?
AGT Labs is an AIHA LAP (IHLAP and EMLAP) and NVLAP accredited laboratory in Houston, TX, holding Texas TDLR Mold Analysis Laboratory License LAB1070. Content is reviewed for technical accuracy by our laboratory team.
Ready to Send Mold Samples?
AIHA EMLAP accredited (LAP-101470) · Texas TDLR Mold Analysis Laboratory License LAB1070. Drop off at 10200 East Freeway, Suite 101, Houston, or ship from anywhere in the U.S.