How long after waterproofing a deck can you still isolate an ignitable liquid?

Area of Science:

• Wood science and material analysis
• Forensic investigation techniques

Background:

• Wood treatments can contain volatile organic compounds.
• Aldehydes in treated wood may interfere with chemical analysis.

Purpose of the Study:

• To determine the persistence of medium petroleum distillate (MPD) in wood.
• To assess potential analytical interferences in fire investigations.

Main Methods:

• Application of Thompson's WaterSeal to wood samples.
• Exposure to outdoor environmental conditions (hot/dry and cool/wet).
• Analysis using ASTM methods to detect MPD and aldehydes.

Main Results:

• Medium petroleum distillate (MPD) was detectable for 14-16 days post-application.
• MPD was not detectable after 20-27 days.
• Aldehydes present in wood could be mistaken for dearomatized MPD.

Conclusions:

• The volatility of MPD in wood sealants is influenced by weather conditions.
• Fire investigators must submit comparison samples to avoid misidentification of chemical residues.