I generally frame oil paintings and use a slip to create a demarcation between the work and the frame. I find the range of slips for this application increasingly limited. I like the Bianco range and continue to use these a lot but I've had to go to DJ Simons for the gold slips which were previously available at Lion. They also carry many more gallery style mouldings but they are, of course very expensive. I think a look at the American approach to framing 'classical subject' oil paintings especially using the cassetta style, 'built up frames', would be useful for your buyers. They seem to use a lot of black or ebonized frames with gold lining slips to great effect, especially on smaller paintings where the 'valued added' is greatly increased, I suppose it's the fashion over there but the effect is extraordinarily good. I very much like the distressed/shabby chic frames Lion have introduced. all in all I find the range of supplies and service very good with Lion, the turnaround is quick and although I'm a small customer I am treated well.