When Ken Kesey and his Mer­ry Pranksters kicked off Haight-Ash­bury’s coun­ter­cul­ture in the 1960s, LSD was the key ingre­di­ent in their potent mix of drugs, the Hell’s Angels, the Beat poets, and their local band The War­locks (soon to become The Grate­ful Dead). Kesey admin­is­tered the drug in “Acid Tests” to find out who could han­dle it (and who couldn’t) after he stole the sub­stance from Army doc­tors, who them­selves admin­is­tered it as part of the CIA’s MKUl­tra exper­i­ments. Not long after­ward, Grate­ful Dead sound­man Owsley “Bear” Stan­ley syn­the­sized “the purest form of LSD ever to hit the street,” writes Rolling Stone, and became the country’s biggest sup­pli­er, the “king of acid.”

What­ev­er uses it might have had in psy­chi­atric set­tings — and there were many known at the time — LSD was made ille­gal in 1968 by the U.S. gov­ern­ment, repress­ing what the gov­ern­ment had itself helped bring into being. But it has since returned with new­found respectabil­i­ty. “Once dis­missed as the dan­ger­ous dal­liances of the coun­ter­cul­ture,” writes Nature, psy­che­del­ic drugs are “gain­ing main­stream accep­tance” in clin­i­cal treat­ment. Psilo­cy­bin, MDMA, and LSD “have been steadi­ly mak­ing their way back into the lab,” notes Sci­en­tif­ic Amer­i­can. “Sci­en­tists are redis­cov­er­ing what many see as the sub­stances’ aston­ish­ing ther­a­peu­tic poten­tial.”

None of this comes as news to San Fran­cis­co fix­ture Mark McCloud. “In the same moral­is­tic man­ner many San Fran­cis­cans pon­tif­i­cate on the health ben­e­fits of mar­i­jua­na,” writes Gre­go­ry Thomas at Mis­sion Local, “McCloud and his friends tout the mer­its of acid.” Next to cur­ing “anx­i­ety, depres­sion and ‘mar­i­tal prob­lems,’” it is also an impor­tant source  of folk art, says McCloud, the own­er and sole pro­pri­etor of the infor­mal­ly-named “LSD Muse­um” housed in his three-sto­ry Vic­to­ri­an home in San Fran­cis­co.

His mis­sion in cre­at­ing and main­tain­ing the muse­um for­mal­ly called the Insti­tute of Ille­gal Images, he says, is to “pre­serve a ‘skele­tal’ rem­nant of San Francisco’s drug-induced 1960s lega­cy, ‘so maybe our chil­dren can bet­ter under­stand us.’”

Specif­i­cal­ly, as Cul­ture Trip explains, McCloud pre­serves the art on sheets of blot­ter acid. As is clear from the many pop cul­tur­al ref­er­ences on blot­ter art — like Beav­is and Butthead and tech­no artist Plas­tik­man (who named his debut album Sheet One) — the 60s blot­ter acid lega­cy extend­ed far beyond its founders’ vision in under­ground scenes through­out the 70s, 80s, 90s, and oughts.

Also known as the Blot­ter Barn or the Insti­tute of Ille­gal Images, McCloud’s house is locat­ed on 20th Street between Mis­sion and Capp. The house pre­serves over 33,000 sheets of LSD blot­ter, treat­ing them like tiny lit­tle works of art. Most of the sheets are framed and hang­ing on McCloud’s walls, dec­o­rat­ing the home with vibrant col­ors and pat­terns, and the rest are kept safe in binders. The house also fea­tures a per­fo­ra­tion board, allow­ing McCloud to turn any work of art sized 7.5 by 7.5 inch­es into 900 pieces, as is typ­i­cal for LSD blot­ter sheets.

McCloud has faced intense scruti­ny from the FBI, and on a cou­ple of occa­sions — in 1992 and again in 2001 — arrest and tri­al by “not very sym­pa­thet­ic” juries, who nonethe­less acquit­ted him both times. Despite the fact that he has a larg­er col­lec­tion of blot­ter acid sheets than the DEA, he and his muse­um have with­stood pros­e­cu­tion and attempts to shut them down, since all the sheets in his pos­ses­sion have either nev­er been dipped in LSD or have become chem­i­cal­ly inac­tive over time. (The museum’s web­site explains the ori­gins of “blot­ter” paper as a means of prepar­ing LSD dos­es after the drug was crim­i­nal­ized in Cal­i­for­nia in 1966.)

“What fas­ci­nates me about blot­ter is what fas­ci­nates me about all art. It changes your mind,” says McCloud in the Wired video at the top of the post. None of his muse­um’s art­work will change your mind in quite the way it was intend­ed, but the mere asso­ci­a­tion with hal­lu­cino­genic expe­ri­ences is enough to inspire the artists “to build the myr­i­ad of sub­ject mat­ter appear­ing on the blot­ters,” Atlas Obscu­ra writes, “rang­ing from the spir­i­tu­al (Hin­du gods, lotus flow­ers) to whim­si­cal (car­toon char­ac­ters), as well as cul­tur­al com­men­tary (Gor­bachev) and the just plain dement­ed (Ozzy Osbourne).”

The muse­um does not keep reg­u­lar hours and was only open by appoint­ment before COVID-19. These days, it’s prob­a­bly best to make a vir­tu­al vis­it at blotterbarn.com, where you’ll find dozens of images of acid blot­ter paper like those above and learn much more about the his­to­ry and cul­ture of LSD dur­ing long years of pro­hi­bi­tion — a con­di­tion that seems poised to final­ly end as gov­ern­ments give up the waste­ful, pun­ish­ing War on Drugs and allow sci­en­tists and psy­cho­nauts to study and explore altered states of con­scious­ness again.

Relat­ed Con­tent: 

Artist Draws 9 Por­traits While on LSD: Inside the 1950s Exper­i­ments to Turn LSD into a “Cre­ativ­i­ty Pill”

When Michel Fou­cault Tripped on Acid in Death Val­ley and Called It “The Great­est Expe­ri­ence of My Life” (1975)

New LSD Research Pro­vides the First Images of the Brain on Acid, and Hints at Its Poten­tial to Pro­mote Cre­ativ­i­ty

Josh Jones is a writer and musi­cian based in Durham, NC. Fol­low him at @jdmagness