Baltimore & Ohio Questions

I'm trying to keep my model railroad as genuine to the time period 1938 to 1948 as possible.
Question: When did the B&O begin using thier large billboard initials
on boxcars and other freight?
Question: When did the B&O begin applying thier Sentinel Service paint scheme on boxcars and other freight?
What few pics I've seen from this time frame show the small lettering & logo only. Your experience and insight on this subject is extremely important to me.
Thanks in advance!!
osteamnut
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

This time I Will say it: dags.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.