Microscale Inc
Decal Setting Solutions

Micro Sol
Walthers Part # 460-105, p. 230 Walthers 2012 HO Scale Reference
A scale, $3.50, currently in stock at Walthers

 
Setting solutions soften decal film, allowing it to stretch over details for the best appearance. Prevents air bubbles and results in an invisible carrier film, reducing silvering. Formulated especially for Micro Scale decals, can be used with most other brands.
 
A stronger formula, for use on larger details or stubborn areas. Just brush on and let it works, actually makes decal part of the paint.