ZAPEL BOGUCHWALA. 1938 - this day) www.zapel.com.pl
Porcelain factory "Ciechów". www.ciechow.com.pl
"Giesche". Probable to 1949.
"ELEKTROPORCELANA BRZEZINKA" Before 1939. 
Brzezinka in 2nd war time. Name "BRZEZINKA" was change to "BIRKENTAL"
"Cmielow" 1918 - 1939
"CMIELOW" before 1918. Factory belonged to Drucki - Lubecki and His family crest is in logo.
In 40's and 50's everythink electric eqipment has that mark
Mark from insulator who was make in pnt norm (Polska Norma Teletechniczna from 1933). I don't know what factory is it. I have three sizes telephone and one n80 porcelain energetic insulator with sp logo.
MARKS FROM POLISH GLASS INSULATORS
Huta Szkła Rogów. Rogow's glass factory. 
Huta Robotnicza Nadburzanka (HRN). 
"VITRUM" 
J. STOLLE "NIEMEN" Glass factory "Niemen" belonged to J. Stolle.
FOREIGN INSULATORS MARKS
Charlottenbrunn. Factory started in 1859 and in 1920 was close. Factory belonged to J. schattel.
Porzellanfabrik Hermsdorf-Klosterlausnitz (the oldest mark (before 1913. I have three two part delta insulator with that logo.
Porzellanfabrik Hermsdorf-Klosterlausnitz (1913 - 1923). 
I found only one insulator with schomburg logo. 
Königliche Porzellan Manufaktur Berlin.(mark from insulator and from catalogue)
"SONNENBERG".If in logo is two digits, it is date.
That insulator was make in 1921. .
Rosenthal Isolatoren 
Closter Veilsdorf 
Eagle and CT letters was the mark of Altwasser factory. Left mark is from insulator and right mark is from porcelain catalogue.
Porzellan-Industrie-Aktiengesellschaft Berghaus. Thanks for Gunther Urlych Aselmeyer. 
Not identified German mark. I have two insulators with that mark. One old telegraph insulator and one n-80. N-80 have market type n 80 in gothic font.
Next not identyfied German mark. 
Letter "S". I have that green piece with that mark and one big high voltage suspension insulator. Green piece was make before 2nd war. Suspension was make in 1970,s 
not identified German mark from old n-80 insulator. 
not identified German mark from old n-80 insulator.
not identified German mark. 
Kuznecov's porcelain factory. Left mark is from insulator and right is from plate from 1910.
Not identified Russian mark. It was used before 1st war 
That mark is from simillar insulator that upper mark. I think that insulator was make near by rewvolution.
Kormilov's Brothers factory mark. on left mark from insulator and on roght mark from tabble porcelain.
North Korean (DPRK) mark. Everythink my insulators with that mark has simillar polish insulator. 
Elektroporcelan Louny, Czech Republik www.epl.cz
not definied Mark from big high voltage delta insulator. Insulator was make in 3th of August 1939.
not definied magk from telephone insulator. Probable it is German mark.If You have some questions or information about that marks please mail to me:
michal_ok@poczta.onet.pl