Despite this tragedy, Hubert’s widow along with their four children, decided to continue the expansion that was planned before Hubert’s death. Construction began in 1950 and a new brewing hall was ready for use in 1952, which is still in use during the winter months today. Of Hubert’s four sons, his oldest son Paul went to work at the brewery. His brother André joined him in 1958, after he finished his military service. The start of Paul’s political career came in 1958 after being elected mayor of Kobbegem. The demands of his political career would later compel him to sell his shares in the brewery completely. Though the De Keersmaeker Pils beer ballooned to 60% of the overall production by 1960, its popularity eventually fell, and by 1972 André was back to producing just lambic.
In [[Books#Geuze_.26_Kriek:_The_Secret_of_Lambic_Beern|''Geuze & Kriek: The Secret of Lambic'']], Van den Steen, says “the Mort Subite name appeared two years previously in 1970, when a well-known Brussels café and geuze blending business A la Mort Subite was taken over from the Vossen brothers”, some of which was purchased from the [[Brasserie De Keersmaeker | De Keersmaeker]] brewery. Eventually, [[Brasserie De Keersmaeker | De Keersmaeker]] took over the name and the Geuze Den Hert became Geuze Mort Subite. Mort Subite made its appearance in Belgium and France, and as early as 1984 in the United States.<ref name=GeuzeKriek>Jef Van den Steen, [[Books#Geuze & Kriek: The Secret of Lambic Beer|Geuze & Kriek: The Secret of Lambic Beer]], 2012</ref>
In 1985, [[Brasserie De Keersmaeker | De Keersmaeker]] hired a new brewer, Bruno Reinders, who was only twenty years old at the time. By 1989, [[Brasserie De Keersmaeker | De Keersmaeker]]r was looking to acquire other breweries, and eventually acquired [[Brasserie Eylenbosch|Eylenbosch]] in Schepdaal, not for brewing but for storage. Additionally in 1989, Paul De Keersmaeker sold his half of the brewery to the Alken-Maes group. At this point, overall quality began to suffer and numerous infections plagued the brewery. To combat this, a new production manager, Marcel Lebeau (previously of [[Brasserie_Belle_Vue|Belle Vue]]) was appointed.<ref name=GeuzeKriek>Jef Van den Steen, [[Books#Geuze & Kriek: The Secret of Lambic Beer|Geuze & Kriek: The Secret of Lambic Beer]], 2012</ref> Lebeau ascertained that the problem was originating in the coolship which was too small and too deep, and that it could not handle the amount of wort being pumped into it. To combat this problem, he began to divide the batches in two and pump half into a steel tank which was filled with regional air. When analysis showed that the batches pumped into the tank picked up as much wild yeast to initiate fermentation, the coolship was eventually retired all together. This method, known as the "Lebeau Method", was a modified version of the [[Brasserie_Belle_Vue|GKZ Method]] used at Belle Vue to help reduce infection and increase product consistency. <ref name=GeuzeKriek>Jef Van den Steen, [[Books#Geuze & Kriek: The Secret of Lambic Beer|Geuze & Kriek: The Secret of Lambic Beer]], 2012</ref>