Source for lead primer

I did a quick search of the companies that offer lead white and all have some calcium carbonate in their grounds. The difference between a lead white ground and a lead white paint is the percentage of oil. Lead white paste indicated by the older painting manuals is generally not available today. When I was a more active painter, I would sometime put a blob of a pure lead white paint on paper and absorb some of the oil to make a leaner ground. One can take this too far and create an underbound paint.
Having written the above, I do want to ask why are you requiring that your ground have no calcium carbonate in it? The practice of adding chalk to a ground to lower expense but also to add tooth goes back to the old masters. It was also common to use cheaper, coarser lead white in the grounds and more refined, expensive lead white in the paint proper.
If you really need calcium carbonate free lead primer, perhaps one of the smaller oil paint companies will make a custom paint for you. I would first start with those companies that respond to questions on MITRA as they clearly are interested in the needs of artists rather than only profit

Are you looking for a lead oil primer that does not contains marble dust, but contains other extender pigments, such as barite? A lead oil primer without extender pigments is simply lead white oil paint.

Thanks George.
So, it turns out that contemporary tubed lead white oil paint with no additives, fillers, or stabilizers would be a fine substitute for what the poster wants.  There are few companies that make a lead white like this, but it is available. 

​For purposes of comparison to modern lead white primers: Dutch Boy Lead White, the the lead white paste once commonly used as an artist’s primer, was originally 89% white lead, 9% linseed oil, 2% turpentine. It was reformulated later to 88% white lead, 10% linseed oil, 2% mineral spirits. A ready-to-use Dutch Boy lead white house paint was also available (too fat for use as a primer), composed of 72% pigment dispersed in a linseed oil/mineral spirits vehicle with 5% drier added. Because they were primarily sold as house paints, these products were banned in the US in 1978. White lead paste still sold for marine applications is not the Dutch Boy formula, having 60% lead along with “putty fillers”.

​Matthew, that was my understanding as well. I have early 20th century house painting manuals which state this. I did not bring it up since it is really not available today. I am glad that you did, though, as it is important to understand this when refering to older manuals which include recomendations about materials.

Reading through this thread I realized that I screwed up and wrote National Lead when I meant Dutch Boy. I actually have a can of this from the 1950s and surprisingly it has not dried up. This is probably because it does not have added driers. Contrary to the general opinion, lead carbonate does not greatly speed up drying unlike litharge and red lead.
Finally, I have been corresponding the George O. off thread and he told me that their lead white oil paint is 88% lead white pigment and 12% oil. This is very close to the “gold” standard in the past. Other manufacturers may make a similar product but I have not seen their percentage breakdowns.

​Brian, thanks for the acknowledgement. I mainly posted for the benefit of readers who might need some context. 

​Matthew, you are more than welcome. Your contributions here are invaluable.

I might be wrong, but the question could be related to the smoothness of the primer. We recently were asked a similar question where the artist wanted a chalk-free lead oil ground, because they wanted to prime aluminum panel with a traditional lead ground with minimal tooth. As Brian mentioned already, additions of chalk and pigments to oil grounds date back to the advent of oil painting. A great resource on historical grounds is Maartje Stols-Witlox’s PhD thesis, which is available online: https://dare.uva.nl/search?identifier=d857e372-47a7-4afe-aa70-df209368ee9d
 The increased tooth and absorbency that comes with the addition of calcium carbonate to oil grounds is intended to optimize the painting experience. It makes the oil grounds feels drier and provides more brush drag which seems to pull the paint from the brush more uniformly. Strokes tend to be more uniform looking and initial washes or applications can more easily be made to look uniform. Calcium also keeps the film matrix open which allows more oxygen into the film and more solvent to escape early in the drying process, if solvent was added for thinning. Compared to Williamsburg Lead Oil Ground WB Flake White paint contains very small amounts of calcium carbonate to modify the feel, beeswax to stabilize the paint and drier. If a perfectly smooth primer is desired, than a lead primer might not be the best choice as lead grounds should not be sanded at all. One could paint directly on aluminum or Dibond, but these surfaces are very slick to paint upon and create very well defined be single brush strokes. A good alternative could be priming with acrylic gesso and sanding in-between layers to get the smoothness but a little absorbency.    
 Generally were are always happy to make custom paints for artists, but lead white might offers additional challenges due to H&S concerns as we are not set up to make small batches of it. If you were seriously interested our lab might be able to work around it, so feel free to reach out to our Custom Lab ( https://www.goldenpaints.com/contact_us/custom_lab).