Free Of Heart Center (FOHC).  This is the one specification that will give you the most stable, strong and beautiful timber for your project.  FOHC means that the timber is cut completely outside of the pith, or “bullseye” of the growth rings.  The photo at right shows how FOHC and Boxed Heart (BH) timbers are cut from a log.  o Note the size of the seasoning check in the new boxed heart timber (above left).  This split is probably less than 1/4”, but as it dries over the first few months after installation, the split will have opened to more than 1/2” (above center).  In the Boxed Heart timbers, moisture is trapped in the inner rings, and as the outside dries, surface tension is created through shrinkage.  The inner rings are still full of moisture and have not shrunken, so cracks (seasoning checks) appear as an escape route for the moisture.  This is the point where twisting, bowing, etc is likely to occur. o In FOHC timbers, all growth rings are severed allowing the timber to dry more evenly.  This reduces the size of the checks to about 1/16”-1/8” and results in a very stable timber. #1 & Better Douglas FirThis is the grade of Douglas Fir timber we keep in inventory, and offers the best overall appearance and strength for various applications for the dollar spent.  Below is a simplified chart that explains the difference in grading terminology between different species and grading agencies, and approximately how they compare from lowest (left) to highest (right).  If you ever hear of an “Appearance” grade or a “Select” grade in species other than those indicated on the chart, it’s likely a local or vendor designation of another grade.  Lumber and timber will almost always have a grade stamp on the face, back or ends of the piece if it’s an agency certified grade.  We specifically request that all grade marks are placed on the ends of the piece so that the appearance of each timber is not affected.  In all cases, our paper trail maintains a thorough documentation of the grades we purchase.