Sheet glass manufacture: the float process: reading answers and analysis
How flat glass has been made, from slow hand spinning and marked roller glass to Alistair Pilkington's float process. Molten glass is poured onto a bed of molten tin, and gravity makes both surfaces flat. The passage covers the costly early years of the first plant and today's near-perfect glass checked by automated inspection.
The table (1-5) comes from paragraphs 1 and 2. The diagram labels (6-8) are in paragraphs 3 and 4. The TRUE / FALSE / NOT GIVEN statements (9-13) run in order from paragraph 3 to paragraph 7.
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Questions 1-8 · Table and diagram completion (NO MORE THAN TWO WORDS)
Table and diagram completion (NO MORE THAN TWO WORDS)
Questions 1-8
How to attack this block: The table separates advantages and disadvantages, so match each gap to the right half of the sentence. 'Slow' is already given, so the second drawback is the other phrase. For the diagram, follow the glass: poured in, floating on the metal, carried out at the end.
Question 1
Answer: spinningParagraph 1, third sentence
What was the first method for making clear, flat glass?
The first successful method for making clear, flat glass involved spinning.
Question says → Passage says
Early methods of producing flat glassThe first successful method for making clear, flat glass
Why: The table's second method is 'Ribbon', a one-word name, so this row wants the other method's name. The passage says the first method 'involved spinning'.
The trap: 'Fire finish' is the result of the method, not the method itself. It belongs with the advantages, not in the Method column.
Question 2
Answer: unblemishedParagraph 1, fourth sentence
Also accepted: perfectly unblemished
What state did the glass stay in with the first method?
the glass had not touched any surfaces between being soft and becoming hard, so it stayed perfectly unblemished
Question says → Passage says
Glass remainedit stayed perfectly unblemished
Why: 'Remained' is 'stayed', so the adjective after it fills the gap: unblemished (free of marks). 'Perfectly unblemished' is also accepted, as it's two words.
The trap: 'Clear' and 'flat' are used for the glass too, but they describe all flat glass, not the special advantage of spinning. The advantage is that nothing touched it, so it had no marks.
Question 3
Answer: labour-intensiveParagraph 1, last sentence
Also accepted: labor-intensive / labour intensive
Besides being slow, what was the drawback of the first method?
However, the process took a long time and was labour intensive.
Question says → Passage says
Slowtook a long time
Disadvantages: Slow; ___took a long time and was labour intensive
Why: 'Slow' in the table covers 'took a long time', so the gap is the other half of the sentence: labour intensive, meaning it needed a lot of workers. With or without the hyphen is fine, and American 'labor' is accepted too.
The trap: Don't go to paragraph 2 for 'expensive'. That's the machines of the ribbon method, which the table already lists.
Question 4
Answer: thicknessParagraph 2, third sentence
What could vary with the ribbon method?
This allowed glass of virtually any thickness to be made non-stop
Question says → Passage says
Could produce glass sheets of varyingglass of virtually any thickness
Non-stop processto be made non-stop
Why: 'Virtually any thickness' becomes 'varying thickness'. The gap needs a noun after 'varying', and the 'non-stop' in the next line confirms you're in the right sentence.
The trap: 'Size' or 'width' might come to mind, but they're not in the passage. You must use the passage's word.
Question 5
Answer: markedParagraph 2, third sentence
What was wrong with the glass made by rollers?
the rollers would leave both sides of the glass marked, and these would then need to be ground and polished
Question says → Passage says
Glass waswould leave both sides of the glass marked
Why: After 'Glass was' you need an adjective or past participle. The rollers left both sides marked, so the glass was marked.
The trap: 'Ground and polished' are what happened to fix the marks, not the problem itself. 'Rubbed away' is the next bullet, already given.
Question 6
Answer: glassParagraph 4, second sentence
Also accepted: molten glass
What is poured into the float bath at the start of the process?
when pouring molten glass onto the molten tin, the underside of the glass would also be perfectly flat
Question says → Passage says
label 6pouring molten glass
Why: In the diagram the material flowing in from the furnace end is what's being poured, and the passage says you pour molten glass onto molten tin. 'Glass' or 'molten glass' both work.
The trap: Don't swap labels 6 and 7. The glass is poured on top, and the tin is the bath underneath it.
Question 7
Answer: tinParagraph 3, second half
Also accepted: molten tin / metal / molten metal
What is the bed of liquid metal in the float bath?
he had the idea of using a bed of molten metal to form the flat glass… The best metal for the job was tin.
Question says → Passage says
label 7a bed of molten metal / The best metal for the job was tin
Why: The glass floats on a bed of molten metal, and the metal is tin. Any of 'tin', 'molten tin', 'metal' or 'molten metal' is accepted, but 'tin' is the precise answer.
The trap: Some people write 'gravity' because paragraph 4 starts with it. Gravity is a force, not something you can label in the bath.
Question 8
Answer: rollersParagraph 4, fourth sentence
What carries the cooled glass out of the bath?
Once the glass cooled to 604°C or less it was too hard to mark and could be transported out of the cooling zone by rollers.
Question says → Passage says
label 8transported out of the cooling zone by rollers
Why: At the exit end of the diagram the glass leaves the bath. The passage says it's transported out by rollers once it's hard enough not to be marked. Keep the plural.
The trap: Paragraph 3 says the float process eliminated 'the need for rollers within the float bath', so people think rollers can't be the answer. Rollers aren't in the bath, but they do carry the glass out afterwards.
TRUE / FALSE / NOT GIVEN
Questions 9-13
How to attack this block: Q10 is about whose money paid for the plant, and the passage only mentions the company's. Q12 depends on reading past 'unchanged': the principle stayed the same but the product got much better. Q13 rests on what the unaided eye can't see.
Question 9
Answer: TRUEParagraph 3, last two sentences
Did the metal for the float process need particular qualities?
The metal had to melt at a temperature less than the hardening point of glass (about 600°C), but could not boil at a temperature below the temperature of the molten glass
Question says → Passage says
had to have specific propertieshad to melt at a temperature less than… could not boil at a temperature below
Why: The metal had two strict requirements: a low enough melting point and a high enough boiling point. Those are specific properties, which is why tin was chosen. TRUE.
Question 10
Answer: NOT GIVENParagraph 5, first two sentences
Did Pilkington put his own money into the plant?
by 1955 he had convinced his company to build a full-scale plant. However, it took 14 months of non-stop production, costing the company £100,000 a month
Question says → Passage says
investedcosting the company £100,000 a month
Why: The passage only talks about the company's money: Pilkington convinced his company to build the plant, and it cost the company £100,000 a month. Whether he also put in his own money isn't mentioned. NOT GIVEN.
The trap: Some answer FALSE because the company paid. But a company paying doesn't rule out Pilkington adding his own money too. The passage simply says nothing about it.
Question 11
Answer: FALSEParagraph 5, second sentence
Was the first full-scale plant successful straight away?
it took 14 months of non-stop production, costing the company £100,000 a month, before the plant produced any usable glass
Question says → Passage says
instant commercial successtook 14 months… before the plant produced any usable glass
Why: Fourteen months of expensive production without a single piece of usable glass is the opposite of instant success. Then another four months were lost after a service. FALSE.
The trap: The paragraph ends happily with float plants all over the world. That's long-term success from 1959, not instant success.
Question 12
Answer: TRUEParagraph 7, first two sentences
Has Pilkington's process been improved since he invented it?
The principle of float glass is unchanged since the 1950s. However, the product has changed dramatically
Question says → Passage says
improvedthe product has changed dramatically… to almost optical perfection
Why: The basic idea is the same, but thickness now ranges from sub-millimetre to 25 mm and the glass has gone from bubbly to almost optical perfection. Paragraph 6 adds that plants now make near optical quality glass. The process now produces far better results, so TRUE.
The trap: 'The principle of float glass is unchanged' makes many people choose FALSE. An unchanged principle can still be carried out better: the 'However' tells you improvement follows.
Question 13
Answer: TRUEParagraph 7, middle
Are computers better than people at spotting faults in glass?
Inspection technology allows more than 100 million measurements a second to be made across the ribbon, locating flaws the unaided eye would be unable to see.
Question says → Passage says
better than humans at detecting faultslocating flaws the unaided eye would be unable to see
Why: The automated system finds flaws that a human eye can't see at all. If the machine sees what you can't, it's better at detecting them. TRUE.
The trap: There's no direct sentence saying 'computers are better than humans', so people pick NOT GIVEN. 'Flaws the unaided eye would be unable to see' is the comparison.
Rollers were removed from inside the float bath, so people rule them out. They still carry the cooled glass out at the end.
Words from this passage worth keeping
molten(Paragraph 1)
melted into a liquid by great heat
unblemished(Paragraph 1)
without any marks or faults
labour intensive(Paragraph 1)
needing a lot of workers or hard work
eliminating(Paragraph 3)
removing completely
fortunate coincidence(Paragraph 4)
a lucky chance that two things matched
simultaneously(Paragraph 6)
at the same time
marred(Paragraph 7)
spoiled or damaged
upstream(Paragraph 7)
at an earlier stage of a process
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The full Cambridge 8 Test 2 reading paper: all three passages, 60 minutes, marked the second you finish with a review of every answer. Already done it? Take it again and see if the same traps still get you.
Cambridge IELTS 8, Test 2, Reading Passage 1. The passage and questions belong to Cambridge University Press and are not reproduced here. We quote short extracts only as evidence for our own commentary, and the answers are published for self-marking. Get the book for the full text, or sit the test on Langujet.
The rest of Cambridge 8 Test 2
Passage 1 · Questions 1-13 · You're hereSheet glass manufacture: the float process
