How dry should a hoof be for good “glue” adhesion?
[With thanks to Vettec for original info: http://vettec.com/content/how-dry-should-foot-be-vettec-products]
Because Acrylic adhesive products will bond to many surfaces, even damp ones, it is critical that moisture in the hoof be checked before “glue” application. Since the first use of adhesives in the equine industry, all suppliers of adhesives (acrylic & urethane) have asked that before applying adhesives, you assure a dry hoof wall. All hooves contain some natural moisture but any excess must be managed for adhesives to achieve an appropriate bond. Notice the moisture ring in the picture; this is the natural moisture that a hoof produces, even if it appears dry. So how do you know if the hoof is dry enough for optimal bonding? Vettec (supplier of urethane adhesives & packing for equine applications) did some experimentation with a Digital Moisture Meter to find out.
The digital moisture meter (pictured) is an inexpensive tool (~$35 USD) that can be found at many hardware stores. The meter offers accurate moisture level readings for wood, plaster, concrete, drywall and, not surprisingly, hooves!
It turns out that the optimal moisture level for ideal adhesion is about 5 -7%. Anything less than ~ 10% works quite well. To determine the moisture level in the hoof, place the meter’s prongs against the hoof wall. In moments you’ll get an accurate reading. If the level is over 10%, use a heat gun to dry the hoof. In the absence of a moisture meter, check to assure there is no moisture ring when the foot is put down after trimming. No moisture ring on the ground generally means the foot should be dry enough. If in doubt, use a heat gun for or hair dryer to give the adhesive a reasonable chance to do its job.