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Lead, 1978...

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• Secretary of the Interior Standards for Rehabilitation

Briefs, energy conservation
• John C. Leeke, Historic Homeworks.

Introduction

A cautionary approach to paint removal is included in the guidelines to the Secretary of the Interior Standards for Rehabilitation. Removing paints down to bare wood surfaces using harsh methods can permanently damage those surfaces; therefore such methods are not recommended. Also, total removal obliterates evidence of the historical paints and their sequence and architectural context.

This Brief expands on that advice for the architect, building manager, contractor, or homeowner by identifying and describing common types of paint surface conditions and failures, then recommending appropriate treatments for preparing exterior wood surfaces for repainting (1) to assure the best adhesion and greatest durability of the new paint.

Although the Brief focuses on responsible methods of "paint removal," several paint surface conditions will be described which do not require any paint removal, and still others which can be successfully handled by limited paint removal. In all cases, the information is intended to address the concerns related to exterior wood. It will also be generally assumed that, because houses built before 1950 involve one or more layers of lead-base paint, (2) the majority of conditions warranting paint removal will mean dealing with this toxic substance along with the dangers of the paint removal tools and chemical strippers themselves.

Purposes of Exterior Paint

Paint (3) applied to exterior wood must withstand yearly extremes of both temperature and humidity. While never expected to be more than a temporary physical shield — requiring reapplication every five to eight years — its importance should not be minimized. Because one of the main causes of wood deterioration is moisture penetration, a primary purpose for painting wood is to exclude such moisture, thereby slowing deterioration not only of a building's exterior siding and decorative features but, ultimately, its underlying structural members. Another important purpose for painting wood is, of course, to define and accent architectural features and to improve appearance.

(1) General paint type recommendations will be made, but paint color recommendations are beyond the scope of this Brief.
(2) Douglas R. Shier and William Hall, Analysis of Housing Data Collected in a Lead-Based Paint Survey in Pittsburgh, Pennsylvania, Part 1. National Bureau of Standards, InterReport 771250, May 1977.
(3) Any pigmented liquid, liquefiable, or mastic composition designed for application to a substrate in a thin layer which is converted to an opaque solid film after application. Paint and Coatings Dictionary, 1978. Federation of Societies for Coatings and Technology.