I think the best option is a negative film.
You stick it to the board and then use a laminator or clothes iron to bond the film to the board.
I'm using this one:
http://www.octamex.de/shop/?page=shop/flypage&product_id=29&category_id=5848924494118370762daa6f026e22f7&/Tenting__Laminat_fuer_Bestueckungsdruck__1m_kaufen.htmlThe are a different kinds on ebay. Search for "photo resist".
I'm not aware of any wet chemistry to make negative boards, but there are various positive photo resist products that are sprayed on or the board or you dip the board in it. I have not tried this, but I have heard it's hard to get consistent results with the spray products.
Emil
On 02-09-12, Kevin Byrne <kbyrne10@...> wrote:
> A question for you chemical experts out there: If this question is not off topic: if it is let me know and I will stop.
>
> I have a large amount of copper clad boards with no positive or negative devolopement solution on them. Is there
>
> a chem. that I can brush or spray onto these boards to turn them into boards ready for positive or negative developement type boards?