After some building and restoration works on my house, I was left with many different wall finishes, some new and unpainted, others older and previously painted. I decided I needed to repaint the whole outside of the house to provide a visual uniformity. Surfaces varied from new pebble-dash with chippings to old pebble-dash that had been painted, and some brushed-finished rendering to new coarse rough-cast (which should not need painting!).
So I turned to eBay - and purchased an electric spray-gun - thought I would do the job in a few days! How wrong I was to believe that!
The paint I selected was Kalon's "Granocryl", a brilliant white wall-coating with a 10-year guarantee (provided it was applied in accordance with manufacturer's instructions of course). I loaded the electric spray-gun to make a start but all I achieved was a slow dribble of paint from the gun. The paint was too thick for spraying. I contacted Leyland Technical Department and was advised that the maximum dilution of the product should be 2.5%. I did try this but to no avail - even going so far as a 10% dilution with no better results. Clearly, spraying was not the answer.
I reverted to brush painting, starting with the most difficult rough-cast surface. The work was laborious and time-consuming and with experimentation I found that a 2-inch brush gave the best results due to the high relief of the rough-cast. I also found that my estimate for paint quantity was far too low - one wall of around 30 square metres needed 30 litres of Granocryl to provide the required two coats. One coat was a vast improvement on visual appearance, but being a rough-cast wall, the paint when dried revealed many tiny holes from bubbles caused by brushing on the rough surface - thus a second coat was imperative. That done, a few months and much rain later, this wall still looks as good as new!
I have provided this account to help anyone considering re-painting their house. I would highly recommend the Kalon "Granocryl" Smooth Finish Wall Coating - a consistently dense and durable wall coating. It may be that industrial high pressure air compressor-driven spray equipment could handle spraying this product, but I was not in any position to try that for myself. One word of warning however - this paint product is tenacious in adhering to any surface and once dry is virtually impossible to remove completely. Thus it is wise to protect drain goods, fascia boards and window frames before painting. I have over many years used various Kalon paint products (including Leyland, Manders, Smyth-Morris and other sub-brands) and have always found them to be superior products.
The moral of this story is - don't rush out and buy something to do a job just because you can (eBay is so great for buying just about anything) - ask around first, find out others' experiences, call the paint manufacture FIRST, and then you will have the information on which to make an informed decision. I have not wasted money on the electric spray-gun, as I will use it for spraying timber treatments on wooden sheds, etc.