Cupping in solid oak tables can indeed be a result of fluctuations in humidity and temperature. Wood is sensitive to changes in its environment, and when the moisture content of the wood changes, it can lead to issues like cupping, warping, and cracking. Here are some recommendations and resources to help you address and prevent such issues:
1. **Maintain Stable Environment:**
- Keep the indoor humidity levels as stable as possible. Fluctuations can cause wood to expand and contract, leading to issues.
- Use air conditioning or a dehumidifier to control humidity during humid periods.
- Avoid placing your furniture near heat sources like radiators or direct sunlight, as they can cause localized drying and warping.
2. **Ideal Humidity Range:**
- The general consensus for indoor humidity to prevent wood issues is around 40-50% relative humidity.
- You can use a hygrometer to monitor humidity levels in your home and make adjustments as needed.
3. **Temperature Considerations:**
- While temperature fluctuations can contribute to humidity changes, keeping the temperature relatively stable is also important for preventing wood issues.
4. **Furniture Placement:**
- Avoid placing your furniture in areas with extreme temperature variations, such as near doors or windows that are frequently opened.
5. **Wood Care:**
- Use a quality wood conditioner or furniture polish to maintain the wood's moisture content and protect it from drying out.
6. **Resources for Further Reading:**
- The Forest Products Laboratory (FPL) of the USDA Forest Service offers a guide called "Wood Handbook: Wood as an Engineering Material," which provides comprehensive information about wood properties, including its response to humidity and temperature changes.
- The National Wood Flooring Association (NWFA) also provides resources on maintaining wood floors, which can be relevant for furniture care as well.
- The American Institute for Conservation of Historic and Artistic Works (AIC) has publications on preventive conservation for wood artifacts, which can offer insights into maintaining wooden furniture.
Remember that wood is a natural material and will always have some degree of response to its environment. It's important to strike a balance between maintaining the aesthetic and structural integrity of your furniture while considering the realities of your specific climate and home conditions. If the cupping is significant and you're concerned about your tables, it might also be a good idea to consult with a local woodworking professional or furniture restorer who is familiar with your region's climate challenges and can offer tailored advice.