1. Long straw. Be sure to ask your source is the bales are long straw or chopped/thrashed straw. A bale harvested by a combine will be thrashed straw and the short pieces make for a very weak bale. These are a poor choice for building. A long straw bale will typically be 14″ tall (2-string) and 16″ tall (3 string).
2. Look for a cut edge and a folded edge. If the cut edge is not clearly visible on one SIDE of the bale, it is probably a thrashed bale and the “cut edge” is likely facing up or down. Again, don’t buy these bales.
3. Color. You want a bright, golden color. Brown or black bales have seen moisture damage. Dull bales may have been stored for a season or longer. They can be acceptable if the other details check out; however, fresh bales are best if you can find them.
4. Moisture Content. Bales should be around 8-13% moisture content when checked with a bale probe. Under no circumstances should the bales reach higher than 20%. At that level, mold growth is supported.
5.Density. The easiest test is to pick up a bale by one string. If the bale deforms in any way, then don’t buy the bales. If the bale stays completely in shape, then the density is acceptable.
6. Shape. tight, rectangular bales are what you want. check the corners of the bales to make sure they are not rounded. Rounded corners will mean a lot of stuffing after the wall is stacked. Tight, angular corners mean the bales will fit together well and your stuffing will be limited.
7. Smell. This is another test of moisture. When you walk into the barn, take a deep inhalation through your nose. How does the room smell? Musty is not a good sign. Fresh straw is what you want to smell.
8. Weight. Dry bales will be relatively light weight. A 2-string bale should not wiehg more than say 45lbs. If it’s heavy (you’ll know what heavy means when you feel it) the bale is probably wet.
Most importantly, use your common sense. If something seems off, it probably is. The importance of quality bales can’t be stressed enough. If you get bad bales, you will fight them from the moment they arrive on site to the moment you finish the house. They make for more retying, more stuffing, more material loss, more post stacking compression, less effectiveness of wall clean up (string trimmer work), weaker vertical stands and corners, more tamping to get your walls plumb, weaker plaster substrate and more. Trust me, get quality bales.
Happy (quality) baling!