Husson Inc.

Woodworking
Husson Products & Services
Husson Products & Services (PDF)

Nemschoff, Inc. Case Study
Nemschoff, Inc. Case Study (PDF)

Perfect Finishing (PDF)

Controlling Humidity Helps Increase the Bottom Line (PDF)

Dust measurement on surface treatment (PDF)


Drying of processed wood (PDF)

Optimum conditions
for sandpaper (PDF)

Loss of water and chemicals with
spray gun (PDF)

Effect of Relative Humidity on evapor-
ation speed (PDF)

Principle for electro-
static spraying (PDF)

Furniture and cabinetmakers as well as other manufacturers of wood-based products throughout North America routinely face manufacturing and indoor air quality problems caused by dry air, especially during the winter “heating season.” Problems include warping and dimensional changes, shrinkage, checking, splitting and cracking, as well as problems with gluing, painting, finishing, and a variety of problems related to static electricity.

All of these problems can affect product quality, wood waste, rework, throughput speeds, run time and delivery schedules.   

Air quality issues usually involve health issues and can include dust, allergy, colds, flu and asthma. Dermatitis and other dry skin problems are also common. Under some circumstances, the combination of wood dust and static electricity can also lead to the potential for fires and explosions.

The ideal climate for woodworking is 35%-50% humidity, at 68°F-72°F.


Equilibrium Moisture Content (EMC) 

The moisture content of wood, below the fiber saturation point, is a function of both relative humidity and temperature of the surrounding air (vapor pressure). Equilibrium moisture content (EMC) is defined as the moisture level at which wood is neither gaining nor losing moisture. When a substance is no longer releasing or gaining moisture equilibrium exists. Reaching optimum EMC through proper relative humidity (RH) control throughout the entire cycle of transportation, storage, manufacturing, finishing and painting, semi-finished and finished goods storage, will have a substantial positive impact on process efficiency while reducing material waste.

Kiln-dried lumber is typically 6.0%-11.0% moisture content. Wood is hydroscopic, readily absorbing or releasing moisture, depending on RH levels in the area. Wood which is stored and worked at RH levels that ensure stable moisture content, stays dimensionally stable and results in fewer manufacturing problems.   

When winter air is heated, humidity levels routinely drop to as low as 10% RH, or even lower. RH levels under 30%-40% reduce moisture content in wood and lead to dimensional changes, including shrinking or swelling, warping, cupping, checking, checking and splitting.

Wood problems can cause reduced machine speeds, machine stops and re-sets, and poor product quality. The result is predictably low numbers in production efficiency, increased machine and tool wear and tear, higher numbers of rejects, re-work and wood waste.


Static Electricity

Static electricity occurs when dry air leads to electricity build-up on wood surfaces. Static electricity can cause a variety of problems, from dust fires and explosions to poor paint or glue adhesion and problems with the uniformity and color of varnishes. Static electricity elimination greatly reduces suspension of wood dust throughout the manufacturing environment.


Dimensional Changes

Woodworking - wood warp

Improper RH conditions affect all aspects of wood material size. Dry wood and wood parts will shrink, warp, cup, check or split causing problems when the wood’s shape or size no longer meets specifications for machining, planning, shaping, gluing or assembly.

Gluing and Laminating



Glues and adhesives don’t cure completely and uniformly in dry air conditions. Ill-fitting pieces are frequently subject to gluing problems. Dry air can often lead to glue joints separating or veneers popping off the base wood as dimensions change or pieces twist and pop. In many cases, these problems present themselves after the finished product has left the manufacturing plant.
 

The Solution: Humidity Control


All of these problems can be avoided or reduced dramatically by maintaining humidity levels at 40%-50% RH in your office, warehouse, manufacturing, finishing and finished goods storage areas. Virtually all plant areas require humidification control to maintain proper humidity levels, especially when air is heated in winter months.

Woodworking


Home | Company | Technical | Core Businesses | Products | Hygiene | References | Contact | Sitemap
Husson Inc. | 1860 Renaissance Blvd. Sturtevant, WI 53177 | Phone 262-884-4669 | email: husson@hussoninc.com