Dimensional stability proves to be an important factor affecting the quality of wooden products. As a sort of crude and thermoplastic resin, shellac excreted by lac insects demonstrates water-repellent and environmental-friendly features. The research impregnated shellac with wood at room temperature and with a vacuum-pressure procedure. Efforts were made to examine how shellac treatment affected the dimensional stability, moisture absorption, chemical structure, thermostability, as well as morphological characteristics of wood. Results indicated that shellac treatment was a type of efficient solution useful in the enhancement of the dimensional stability of wood. Shellac solution had good permeability in the wood, and the weight percentage gain reached 13.01% after impregnation. The swelling coefficients of treated wood in the tangential and radial directions decreased by 20.13% and 24.12%, respectively, indicating that impregnation could improve wood dimensional stability. The moisture absorption of shellac-treated wood was reduced by 38.15% under 20 °C and 65% relative humidity. Moreover, shellac treatment significantly modified wood structure, although there were no drastic changes in the spectra. Specimens for shellac treatment ran across two decomposition peaks at 350 and 390 °C, and specimens in the control group saw one more common derivative thermogravimetric curve when the sharp peak approached 355 °C. After impregnation of shellac into wood, the shellac blocked pits and hardened on the intrinsic layer of the wood for fear of hygroscopicity. The practice was applicable to a variety of wood products, such as buildings, furniture, and landscape architecture.

Linseed oil and shellac are natural, environmentally friendly materials with good water repellency. They were used to impregnate Chinese ash wood at room temperature (20 °C) using a vacuum-pressure procedure (consisting of three cycles of 0.01 MPa for 1.5 h and atmospheric pressure for 1.5 h) to improve the dimensional stability of wood. The effects of the impregnation treatment on wood color changes, dimensional stability, moisture absorption, and morphological characteristics were evaluated. The linseed oil and shellac treatment improved the dimensional stability of wood. Linseed oil and shellac displayed good permeability in Chinese ash wood, with weight gains of 21.7% and 19.0%, respectively, after impregnation. The swelling coefficients of treated wood in the tangential and radial directions decreased by 15 to 22%, indicating that impregnation improved the dimensional stability of wood. Linseed oil and shellac solidified and occluded the pits within the wood interior to prevent moisture absorption. This method can be used to improve the dimensional stability of a variety of wood products, such as buildings, furniture, and landscape architecture.

In this study, wood samples extracted from the Taicang ancient ship, dating back to the Yuan Dynasty, were investigated to study the characteristics of waterlogged archaeological wood. The macroscopic characteristics and microscopic structures were used to identify the wood species. To assess the degree of degradation of the waterlogged archaeological wood, X-ray diffraction (XRD), nanoindentation (NI), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to compare the new and ancient wood samples from the same species. The microscopic structures of the samples were identified as Pinus massoniana. The XRD and nanoindentation results revealed that the crystallinity index of the cellulose decreased from 41.07% to 33.85%, the elastic modulus was reduced by 20.90%, and hardness was reduced by 55.6% compared with the new wood. The FTIR spectra revealed that biological deterioration occurred in the cellulose and hemicellulose, but there was no noticeable change in the lignin content. These results provide helpful information for the conservation and restoration of ancient ships.

The Huaguangjiao I is an ancient Chinese wooden shipwreck from the South Song Dynasty (AD 1127–1279) discovered in the South China Sea in 1996. The first phase of its conservation, desalination and desulfurization, was completed in 2016. In this paper, three archaeological wood samples exhibiting different degrees of deterioration from Huaguangjiao No. 1 were consolidated with PEG-4000 and dehydrated via freeze drying and supercritical CO2 drying methods. The dimensional stability, hygroscopicity, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to evaluate the effects of consolidation and dehydration. The results showed that PEG4000 was an efficient consolidation material that also effectively decreased shrinkage during dehydration. Furthermore, both vacuum-freeze and supercritical CO2 drying were efficient methods for treating waterlogged archaeological wood. After PEG4000 impregnation, the shrinkage percentage of the waterlogged archaeological wood became slightly lower than sound wood. The moisture absorption of the experimental specimens ranged within 3.35%–4.53%, and they comprised 50% sound wood, resulting in a marked improvement in dimensional stability. FTIR spectra indicated that impregnation improved wood dimensional stability by reducing hydrophilic groups. These results show that this method can effectively treat waterlogged wood for preservation purposes.

Luoyang No.1 is a Qing Dynasty (1644–1902) inland river ancient wooden shipwreck discovered in September 2013. It adds significantly to the study of Grand Canal transport history and Luoyang’s economic history. The wood characteristics of Luoyang No.1 were investigated in this study using chemical compositions, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nano-indentation (NI), and scanning electron microscopy (SEM). The results showed that the holocellulose content was only 32.84–37.69%, indicating that the cellulose and hemicellulose had been seriously degraded. Based on the XRD pattern, the degree of crystallinity of cellulose in wood ranged from 19.82 to 22.83%. The nano-indentation demonstrated that compared with the undegraded contemporary wood, the elastic modulus and hardness of the ancient ship wood decreased by 45.5% and 32.1%, respectively. Furthermore, the FTIR spectra revealed that the biological deterioration of ancient wood was indicated by a decrease in the peaks related to cellulose and hemicellulose, but the change in lignin was insignificant. The results could provide knowledge for appropriate dewatering, strengthening, restoration strategies and regulation of the museum environment.