Abstract The removal of brass-based overpaint, applied during previous restoration, from an oil-gilded frame by the application of solvents can be challenging and difficult to control due to the often similar solubilities of the paint and oil gilding. In this study, Er:YAG laser radiation (2940nm) has been used to remove brass-based overpaint from a discoloured overpainted oil-gilded frame. Tests have been systematically carried out to investigate the effect of changes to: (1) laser parameters (fluence; number of pulses; pulse duration; repetition rate), and (2) choice of pre-wetting agent (water; isopropyl alcohol; acetone) on the removal process. Observations of the irradiated surfaces revealed that the thermal interaction between laser radiation and the overpaint led to decomposition of the overpaint binder which weakened the paint sufficiently to enable removal using a cotton swab. By using acetone as a pre-wetting agent, the overpaint was removed from a small area of the frame by 20 pulses at 0.8J/cm2 (80µs pulse duration; 1Hz) revealing the gold leaf. This investigation demonstrates the potential for Er:YAG laser radiation in the controlled removal of brass-based overpaint from gilded wood and the requirement for further work to optimise the removal process and characterise the ‘cleaned’ surface.

中文翻译：

---

初步研究了使用Er：YAG激光从油镀金框架上去除黄铜基涂料时各种参数的影响

摘要由于涂漆和油烫金的溶解度通常相似，因此从前一次修复过程中使用溶剂从油烫金框架中去除黄铜基涂料可能是一项挑战，而且难以控制。在这项研究中，Er：YAG激光辐射（2940nm）已用于从褪色的油漆过的镀金框架上去除黄铜基油漆。已经系统地进行了测试，以调查以下变化的影响：（1）激光参数（注量；脉冲数；脉冲持续时间；重复率）；和（2）选择预湿剂（水；异丙醇；丙酮） ）移除程序。对辐照表面的观察表明，激光辐射与罩面涂料之间的热相互作用导致罩面涂料粘结剂的分解，从而使涂料充分弱化，从而可以使用棉签清除。通过使用丙酮作为预润湿剂，以0.8J / cm2（80µs脉冲持续时间； 1Hz）的20个脉冲从框架的一小部分去除了罩面漆，露出了金箔。这项研究表明，Er：YAG激光辐射在从镀金木材中有控制地去除黄铜基面漆的潜力以及对进一步工作的要求，以优化去除工艺并表征“清洁”表面。1Hz）露出金箔。这项研究表明，Er：YAG激光辐射在从镀金木材中有控制地去除黄铜基面漆的潜力以及对进一步工作的要求，以优化去除工艺并表征“清洁”表面。1Hz）露出金箔。这项研究表明，Er：YAG激光辐射在从镀金木材中有控制地去除黄铜基面漆的潜力以及对进一步工作的要求，以优化去除工艺并表征“清洁”表面。