Light Asphaltic Oils
Technical Bulletin #12
Current as of JUNE 2019
The occurrence of water soluble light asphaltic oils, also known as "tobacco-juicing" for its color resemblance, is the normal result of the heating and weathering of all asphalt-based products.
These water soluble light asphaltic oils form during certain combinations of weather conditions, usually when high amounts of night moisture are followed by a very clear morning with direct sunlight, or after a prolonged lack of rain with the above conditions immediately following. The residue from these light asphaltic oils presents no harm to the roofing structure and in no way affects the expected longevity or performance of the asphalt based roofing products it is associated with.
The light asphaltic oils, although water soluble, may become a vehicle for any airborne contaminant, such as dust, dirt or any other atmospheric pollutant, and may trickle down and stain fascias or side walls that are not protected by gutters or other diversions. To reduce the effect of this minor aesthetic staining concern it may be possible to wash it off with a mild dish washing detergent; always check a small area first, and check with the siding manufacturer if possible. The use of solvent-based cleaners is not recommended as this may adversely affect any painted or stained surface.
NOTE: The appearance of light asphaltic oils in connection with asphaltic-based roofing shingles, whether visible prior to or after installation, occurs because of natural conditions. It is normal and inherent and weathers off the shingles naturally in due course, and is in no way indicative of an asphalt or product failure.
The information contained in this bulletin is for general education and is not intended to replace advice from a qualified contractor or direction on usage/installation from the manufacturer. Consumers should be aware of the safety hazards associated with work on roofs and, before doing so themselves, should consider following CASMA s advice of using qualified contractors. This bulletin may be reproduced with permission on condition that it be reproduced in whole, unedited, with attribution of copyright to CASMA.
© Copyright 1989 - Canadian Asphalt Shingle Manufacturers' Association. All Rights Reserved.