COACHES Damien Hardwick and Brad Scott have renewed calls to shut the roof at Etihad Stadium after an experiment to keep it half open in Saturday's NAB Challenge clash between Richmond and North Melbourne.

The trial, which will be repeated for Sunday's clash between Carlton and Geelong, saw the western roof panel moved into a different position so more of the field would stay in shade during play as the sun moved.

With roughly 50 per cent of the ground in sunlight for the first half of the match, Hardwick said he noticed midfielders struggling to handle the ball at centre bounces because of the contrast. 

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"I don't know, it's not that hard is it? Is it that hard, really? Here's an idea, shut the bloody thing. Jesus," Hardwick said.  

While the shaded area of the ground slowly expanded in the second half, Hardwick was emphatic that players would prefer to compete under a closed roof.

"If you're in the middle of the ground … it's right in their eyes," he said.

"If you watch the first centre bounce, I reckon there's guys doing this one (missing the football with both hands) trying to catch the ball. It's not rocket science.

"It's OK if the games are a little bit later with the shade contrast to keep it off the people. But the players are pretty important."

The half-open roof left a divide between light and dark on Saturday.  Picture: AFL Media

A fan survey last year saw 60 per cent of supporters wanted the roof open when the weather was fine.

Scott, who has criticised the decision to open the roof in the past, said he needed to choose his words carefully because he was in favour of experimentation through the pre-season competition. 

WATCH: Brad Scott happy with the Roos, unhappy with the roof

The coach said he would like to know the opinion of Saturday's broadcaster, Fox Footy, and supporters watching the game at home.

"My opinion is very, very clear – I've said it before, I will say it again, I think the roof should be closed," he said.

"I think it's better for everyone, but I've stated that before, so that's nothing new.

"They were trying to experiment with different things and that's a great idea.

"Have a look at different things, get all the information and make a decision from there."

The AFL's roof policy will remain the same this year, which means it will be open for afternoon games if the weather forecast permits.