Advanced Sealing Solutions' offer a product for PIC called Ultra, although it's not cheap. If buying small amounts then buy via ebay as carriage way cheaper.
I opted for this after doing quite a bit of research as to PIC sealer. Others considered were PICSeal, Swiss-Seal and Creative-Impressions (who manufacture a sealer they claim can be applied onto damp surfaces; Hrdroseal).
Unfortunately, a day or so after cleaning we had a blizzard!
As the weather is no longer up to it I have agreed to rewash and seal early next year. Therefore, I can't let you know how well it covered. This is where it may be an idea to try Creative-Impressions' Hyrdoseal. If you do let me know how it goes.
The best way to apply the 'Ultra', as per Drew at Advanced Sealing Solutions is to roller the first coat at 45 degrees to the property. After a minimum of one hour, dependant on conditions, roller the second at 90 degrees to the first. If you have experience of spraying then you can spray the second but they still recommend rollering the first coat.
Hope this helps.
One last point, a local company to me (Lichfield) manufacturs and sells coloured sealers. I have had a chat with the owner and he seems to be switched on. I will almost certainly trial next year. They sell on ebay.