The entrepreneurs behind a children's clothing range which changes colour in the rain have set their sights on breaking the American market after smashing their crowdfunding target of £50,000.

The founders of Norwich-based business Holly and Beau are using £89,000 raised on crowdfunding website Crowdcube to develop new products and push a PR campaign in the United States.

Jack and Fleur Passant – the brother and sister duo behind the company – launched the stateside charm offensive on the back of rising sales. Orders are expected to grow three-fold from 45,000 last year to 150,000 by the end of 2015.

The boost has been fuelled by an increased demand from international boutiques in Europe and America after the business was featured at children's trade fares in New York and Paris, and on a US breakfast TV show in Phoenix, Arizona. The firm manufactures the rain jackets and umbrellas – which change colour when wet – in China and exports them to 23 countries worldwide. It is currently searching for its first commercial premises in Norwich.

Mr Passant, 25, of Brunswick Road, Norwich, said the international demand forced the company to think carefully about which markets it wanted to concentrate on first.

'Pushing the American market and securing a department store in the UK is the plan. It is a case of following the demand, but also trying to be realistic in terms of where we can actually supply the products because we have had interest from Russia and the Middle East, but we cannot do every market.'

Despite winning Innovation of the Year at the Nectar Card small business awards 2014, Mr Passant said it was difficult to get the business up and running.

'It has been incredibly tough. The first year was difficult and we were learning along the way, but in the second year everything I pushed for in the first year made the process a lot more straightforward.

'We have got the production set up now, so we can keep up with demand from the suppliers point of view. We are now increasing production. There will be a massive upscale this year and next year will probably be the same. The whole point is to stay here in Norfolk and build one of the strongest childrenswear brands,' he added.

Mr Passant set up the firm with Fleur, 23 in 2012 after leaving his job as an investment broker in the City. Plans are now underway to launch colour-changing swimwear, as well as taking on non-executive directors to guide the business going forward.