Are granite worktops heat resistant?
Tuesday, 26th August 2014, Lucy Mccoy
The modern kitchen can be hard to maintain. We all want them to look as if they were installed yesterday, but cooking is a messy art. The worktop is painted with tomato sauce, stained with wine and bejewelled with the kid's sticky sweets. It's not just stains we have to deal with though, as it's all too easy to forget you've left a hot plate or pan on the kitchen worktop whilst you're trying to get the kids to settle down at the table.
Therefore, it's highly important that the modern work surface is heat resistant, to prevent your beloved kitchen from ageing badly. Granite is a popular choice of worktop due to its luxury look, but just how much heat can it handle?
What is granite?
Granite is a naturally occurring material, which is formed by the slow process of magma crystallisation below the Earth's surface. It's also the most common igneous rock and is used to craft many objects, such as floor tiles, cemetery monuments and paving stones. Each slab is completely unique, which just adds to its beauty. It's no wonder that it's such a popular stone.
Since granite is formed from magma, you'd think that it would be pretty heat resistant, and you're right, it is. Just how much punishment can it take, though?
How hot can granite get?
To see how much heat different work surfaces can handle, Kip Jeffrey, chartered geologist and fellow of the Geological Society, compiled a report which replicated real-life kitchen conditions. Three steel rings, designed to imitate a roasting tin, were heated to three different temperatures: 170°, 200° and 230°. The rings were then left on the worktops for between 15 seconds and two minutes.
The granite surface was able to withstand two minutes of the 230° steel ring without being affected at all, showing that it really can endure high and constant heat. It was a similar story for the quartz and textured laminate surfaces, which were able to deal with just as much heat over the same amount of time without being damaged.
However, some surfaces didn't perform so well. The gloss laminate became the most damaged from the heat, as after just 15 seconds of the 230° ring, significant markings started to appear. Acrylic solid surface was damaged after two minutes on the lowest heat setting and the wood worktop became darker the longer it was exposed to the 230° ring.
Essentially, you'd be hard-pushed to damage your granite worktop. However, it's worth noting that this study only monitored how much heat the surfaces could take for a maximum of two minutes. Potentially, the granite surface may have cracked after five or ten minutes of high heat exposure, so there's no point pushing your luck. You may be able to get away with leaving a hot plate or pan on your worktop for a minute or two, but it's best not to let one of your pots cool on the surface for an extended period of time.
What happens when granite gets too hot?
Granite is able to absorb a fair amount of heat, which is why it can deal with such high temperatures. However if you put a blowtorch to the stone, you'd soon find out that granite can crack due to heat. This is called thermo-shock; the crack itself may only be a hairline, but it can ruin the look of your once beautiful surface
It is possible to buy repair kits or hire someone to come and fix your granite, but unfortunately there is only so much you can do to mend cracks. The worktop may look better after such a treatment, but it won't look as good as it did and you may be forced to replace the whole slab, which can be expensive. For this reason, it's recommended that you use trivets to hold hot objects, instead of placing them directly on the worktop.