Dry peel plies are generally used in composite manufacturing by liquid moulding techniques in the maritime sector. They allow excess resin to bleed through its weaved structure, keeping the surfaces clean, and in certain cases with the required roughness until ready for bonding. However, these plies often contain residues resultant from manufacturing, such as silicone oils or others . These residues can be transferred to the bonding surfaces of the composites and potentially hinder adhesion, which could lead to catastrophic failure of structures when in service. Therefore, the standard practice in the maritime industry is to mechanically abrade and clean the composite surfaces before adhesive bonding or overlamination of joints. This adds a time-consuming step to the process, which may not always be necessary to achieve acceptable adhesion [1, 2]. Optimally this step could be suppressed if the effect and extent of peel ply residues, surface topology, peel ply polarity and material chemistry synergies are well correlated to the joint properties for set materials. A comparative study of the effect of peel ply treatment versus mechanical abrasion and solvent washing of adhesive bonded polyester and vinyl ester glass fibre composites is presented. The presence and distribution of contaminants on the composite and peel ply surfaces was analysed with Tof-SIMS. These data were correlated to the failure mode after compression shear and out-of-plane delamination of these composites. In certain circumstances the chemistry of the adherends matrix resin and the adhesive can play a role on overcoming the presence of some contaminants left by the peel ply on the bonding surface and guarantee a good adhesion bond, i.e. no adhesive failure.