I hope we can keep this thread to discussing Uniters and Fenice. I know there are other good options like Stahl and their primer PH-53, Stilz V600 and their primer Undercoat600, Giardini and their base coat, Kenda farben and other brands. But we could make another thread and discuss them
This will not be a discussion about applying edge paint without primer. The owner of this forum (Philip) has excellent instructions on how to apply edge paint (Maybe we don't all use the same methods, but there are many good methods for preparing and applying edge paint, and it is also a difference between brands) So worth watching his course in edge painting.
I know that Philip as many of us are open to discussing and using new methods, in this case primers.
I have during the years I have done this, mainly used Fenice, and a little bit Uniters. But the products that I have tested for a long time have been painted with Fenice (and no primer) but a first thin coat (heated) and I had some problems with cracking at the folds on wallets with vegetable tanned exterior. I personally do think that primers can improve the durability for some products, especially when they are folded a lot, and with a fiber structure that is less dense or oily waxy.
To not make this topic way to wide, I thought we could focus on Uniters and Fenice in this thread.
I have some thoughts that you guys might be interested in discussing.
So what is the main SOP for application (How I interpret it in my situation) when using a fileteuse? (Philip uploaded a document with the instructions for Uniters, so have a look that also)
Uniters:
Start with an even edge, if flush cut slightly sanded (I prefer to sand in one direction with P400 before any application of paint or primers)
A coat of EP-sealer (Diluted 30% if needed, if the paint doesn't soak in)
Smooth with fileteuse
Sand with P400?
First coat of edge paint, relatively thin.
Keep adding coats and sand and optinal smoothing with fileteuse between layers.
Questions I would like to discuss about Uniters:
If the coat of primer is sanded through, which is likely unless the edge is flush cut as begin with (Which is not always possible) would we benefit from adding a second layer of primer, I can't see that they wouldn't adhere to each other, but we don't know if there is an "opening time" for crosslinking, because the primer and the paint will crosslink with each other.
The SOP for Uniters: https://www.leathercraftmasterclass.com/forum-1/leathercraft-techniques/secret-edge-paint-techniques-by-uniters-finally-revealed
Fenice
Start with an even edge, same as with Uniters
First coat of edge paint, also diluted 30% if needed)
Smooth with fileteuse
Sand to give it a porous surface and make it even
A coat of primer (AR 6250/P or UW 13/8 or UW 13/9 or the common thinner versions)
Questions I would like to discuss about Fenice:
A similar question as with Uniters, if the first coat of edge paint is sanded through, would it be a good idea to apply one more coat before primer. (I can't find this document now, but I think the opening time for crosslinking is two hours for Fenice primers and edge paint, so it would leave enough time for a second coat over a first thin coat (the first coat will dry relatively quick. Edit: Some additional thoughts. I have seen some documents where there are no recommendations of a layer of paint before the primer. One example is the SL-M kit (A mixing kit from Fenice in 250ml bottles, based on the edge paint AR 6450/T (The paint viscosity you usually see in different size bottles sold by resellers) this includes the UW primer/adhesion promoter, and according to the instructions it should be applied before any paint. This makes me think that maybe the SOP recommendations that suggest to start with a coat of paint, is to get a flat uniform edge without leather fibers sticking up. If this is is the case, then it wouldn't really matter if we sand through the first coat a little bit with a finer grit paper like P400. (Amateur thoughts here, so please share your thoughts.)
Should we sand the primer before applying the next coat of edge paint, or paint directly on the primer? probably a good idea to sand slightly with a fine grit sand paper?
Two documents from Fenice that includes SOP for primers.
"If applied to the edge before the final section lacquer" suggest that it will not be a problem to add more layers of paint before the primer. Thoughts?
The funny thing is, edge paint was designed as a fast and cheap way to finish edges instead of relying on more highly skilled artisans to skive and turn an edge.
Strangely it has become THE most time consuming way of edge finishing (if you are looking for near perfection), and requires a lot of skill and planning, depending on the leather and desired outcome. No dog in the fight here, just an interesting observation on how things evolve.
Try this and see what you think. Apply a thin layer of PVA (maybe a little diluted) to a raw edge. Before the PVA dries completely, apply some edge paint so that they bond while mostly liquid.
See what you think.
Regarding a double primer. I doubt the second later will adhere to itself as well as the fist layer adheres to raw leather. But that's an untested theory.
There's some great information there, thank you for sharing!
Regarding sanding the primer, I would most definitely recommend it. As far as I am aware they don't react with each other to create a bond, rather the edge paint simply sticks to the primer surface.
Sanding will definitely increase adhesion, not to mention another opportunity to level the surface.