I am going to copy and paste some info in here that are from some research I did long ago.
July 17, 2018 written by Angie Jones
Primer is a foundation layer that improves paint adhesion. It seals off any possible residues left behind on the vinyl that did not get washed off. It adds “tooth” to the vinyl to grab the paints. You might not actually feel this but it is there. This is why some brands of primer may feel slightly tacky to the touch when dry. This should go away after a couple layers of painting however. If you are not using a specific brand of air dry paints for reborn dolls with a formulated primer, there are other options you can choose. Pretty much anything that says on the side of the bottle that it can be used as a translucent ground will work. From the Golden line, Fluid Matte Medium, Matte Medium or GAC 100 for acrylics all state they can be used as a primer. I have used the Fluid Matte Medium myself and been happy with the results. You just apply a very thin layer of the product with a dense wedge. DO NOT use a porous wedge such as the Swispers brand because they will cause the product to bubble up and dry unevenly on the surface of the vinyl. You want a totally smooth application. You can also tint your primer layer with paint if you wish so as to add a color base while priming. I have done this with both the RebornFX Primer as well as with the Golden Fluid Matte Medium. You just want to make sure your Primer layer is 60% or more of product and no more than 40% paint when doing this. This is to ensure the primer layer is strong enough in sealing properties to prepare the vinyl for successful painting.
WHAT PRODUCT SUBSTITUTIONS CAN WE MAKE?
Lil Dumplins Nursery Reborn Dolls·Saturday, July 13, 2019
I do a lot of talking about different products and mediums that can be used in reborn doll painting and sometimes it can get confusing. In an effort to try to clear up some confusion I will try to start a list here of commonly sold Reborn Doll Paint Mediums by brand names and what alternatives on the art shelf that can be used.
Air Dry Paint: All Air Dry Paints sold for reborn doll painting, regardless of the brand name used, are acrylic paints. Acrylic paint is a fast-drying paint made of pigment suspended in acrylic polymer emulsion. The emulsion contains binders to hold the pigment particles together and aid in adhesion to the surface upon which the paint is applied. What may cause one brand to vary from another is the amount of pigment load in the paint, the light fastness of the paint, and the ingredients used to create the emulsion. There are also other additives such as surfactants that are used to disperse pigments, and anti-foaming agents to stop the paint from frothing as you use it. Lesser quality paints have less pigment load and cheaper ingredients such as fillers, opacifiers, or dyes. This is why I strongly discourage using cheaper grade paints such as craft paints for reborn doll painting. Even among artist grade paints, one brand may produce higher quality paint than another and within one product line there can be different grades such as student grade verses artist grade. When it comes to paints sold under labels specifically for reborn doll painting, there can be a significant variance from one to another as well. However, theoretically, all air dry paints are inter-mixable with each other. If doing this bare in mind mixing a lower grade paint with a higher grade paint will reduce the quality of the higher grade one.
Emulsion mediums: I stated above that paint is pigments suspended in emulsion. Mediums are emulsions developed with varying properties that can be added to paint to thin the paints, thicken the paints, product sheen or matte sheen, create glazes and so on. The use of such mediums also increase the polymer binders load in your paint mix to offset anything you may have added that weakens the polymer binders load such as distilled water and/or retarders. The more I read about products the more I realize that many of them have multiple uses so that it is possible not to need to buy so many separate mediums. Here is a list of mediums that can be used in your paint mix. You need only add ONE of these to your paint mix when creating a wash, mottled layer etc. in reborn doll painting.
So when you see one of these products listed in a tutorial or guide, you can substitute out any other item from the list instead. Just keep in mind the varying amounts of matting agents in each product will affect how much or less sheen your paint layer will have. ---------->>> RebornFX Emulsion, any other artist/reborn painting brand labeled Emulsion, Golden Fluid Matte Medium, Liquitex Fluid Matte Medium, any other other brand artist grade Fluid Matte Medium, Liquitex Ultra Matte Gel, Liquitex Matte Gel, Golden Super Matte Medium, Jo Sonjas All Purpose Sealer, Golden Glazing Liquid Satin-this will leave behind more sheen.
Retarder or Slow Dry: These names are used interchangeably depending on the brand. They are not emulsions but rather are additives. This means they do not contain any binders thus is it recommended not to use more than 25% to paint load. Using too much will lead to instability of the paints and a tacky surface that never seems to dry. Retarders/Slow Drys will thin the paints, decrease drying time, reduce the skinning of the paints on the pallet, increase transparency a bit and aid in the flow of the paints.
Most all brands I am aware of refer to their product either as a Retarder or Slow Dry. The one exception I know of is RebornFX Open Time which was formulated to contain both the Retarder/Slow Dry as well as some binder in the mix. Thus this product can be replaced by using Retarder or Slow Dry of another brand but keep in mind the ratio limitations when using the other brands.
Flow Medium: One of my favorite products to use when painting hair has become Flow Medium. Flow medium can be used to thin paints for air brush painting. When using them in paint mixes with the brush, they are most useful for when you wish to change the paint consistency without changing the color intensity. Flow medium also slightly increases the open time (drying time) of the paints. This is particularly useful when painting hair. I usually still add a couple drops of retarder as well. However, I find adding the flow medium to my paint mix gives my paint the slick gliding consistency that is needed to produce flowing hair lines. Yet it does not dilute the color so you still get nice rich hair color lines that do not lose intensity when dry.
There are other brands of Flow Medium out there but Jo Sonjas Flow Medium is a good one.
Also, Golden has a product called Golden High Flow Medium that is recommend to use with their high flow paints for air brush painting. From all I read, it is very similar if not pretty much the same as the Jo Sonjas brand. I purchased a bottle of it and have used it as well. I like both brands equally well I think. I read on the Hofcraft site that the Jo Sonjas Flow Medium can be used as a very light sealer. This made me think of using it to set Panpastels so one can continue painting over them.
Primer: Many of the air dry paints sold specifically for reborn doll painting have their own primer formula. Primer is used as an undercoat to seal the vinyl surface before painting. It also gives the surface a “tooth” for the paint to adhere to. On canvas the most comment primer used is acrylic Gesso. There is a clear version of acrylic Gesso that could be used on vinyl but most find it too heavy in tooth for vinyl dolls. It does not dry to a totally smooth surface thus it is not preferred. Instead, the best choice is to use an artist grade medium that says it can be used as a translucent ground for painting. When using these products as a primer, you may notice a very slight tacky feel to the surface that may vary from one brand to the next. This should lessen as you paint and go away when matted at the end with matte varnishes.
Some possible choices are---------->>>Golden Fluid Matte Medium, Liquitex Fluid Matte Medium, Golden Matte medium, Jo Sonjas All Purpose Sealer.
Isolation Coat: An isolation coat is a transparent coat between your finished painted work and the varnish. It seals the paints and separates them from the varnish so that a removable varnish can be applied over the paints that can later be removed with ammonia without removing the paint work.
What can we use for this you ask?---------->>>RebornFX has their own isolation coat called RebornFX Sealer. I am not aware of any other marketed reborn doll paint that sells an Isolation coat but if I discover one I will add it to this information.
You can mix your own if you prefer. Golden has long recommend this recipe: Mix two parts Golden soft gel gloss to one part distilled water. Golden now also sells a ready made mix that they call Golden Isolation Coat. I have not tried it myself but I do know that it has a gloss finish.
Another Isolation Coat that can be made with Golden products is by mixing 2 parts Golden GAC500 to 1 part Golden High Flow Medium. This makes a sprayable Isolation coat per their instructions.
I have found that any product that seals off the paint surface before varnishing can work. Since I do not like the sheen associated with most Isolation coats I have tried, I like to just mix Liquitex Ultra Matte Gel 50/50 with Golden Polymer Matte Varnish and apply this as my Isolation coat. The Liquitex Ultra Matte Gel is a polymer emulsion that contains binders that make the varnish permanent and I get a more matte seal. I can then go over this when it dries with the pure Golden Polymer varnish with some added matting agents (like my corn starch method). This creates a varnish layer that is removable or you can use any other brand removable varnish. If you do not care about removing your varnish later, you can just a permanent varnish like the DecoArt/Americana Soft Touch Varnish.
This is all I have for now. If there are any other product discussions that arise later, I will add them to this write up as we go.
*This info below comes from an article I wrote July 5, 2019. *
Some of it is outdated in terms of available products but maybe this will help.
Varnish: The last layer you will want to apply to your pieces is a varnish. TECHNICALLY you do not have to varnish acrylic paints. They are permanent once they are fully cured but they are not fully cured to the vinyl for a month. Using a matte varnish helps to lock everything down even more so to speak. Realistically, if you want your paints to hold up to a lot of handling and play you SHOULD seal them. Sealing the paints gives them an extra barrier against rub off, scratches, and absorption of stains. This is true of all types of paints including Genesis heat set paints. I know some people do not seal their Genesis heat set paints either and I have seen down the road the dolls are very shiny and paint rubbing off. So IMO it is a must to varnish every paint job with something at the end.
You can use Genesis heat set products to varnish your air dry painted pieces if you wish. Most of the artist grade acrylic paints will withstand being heat set after 2 weeks cure time. If you have not allowed enough cure time you may get some yellow or orangish tinge to your paint finish when heat setting it. If this happens giving the pieces a lavender wash usually takes care of that but it can be upsetting to see. LDC brand paints are the worst ones to go orange when heat set.
For air dry varnishes, I have shared in the past my preferences are now to use Golden Polymer Matte Varnish or DecoArt or Americana Soft touch varnish and mix the varnish with corn starch (and diatomaceous earth if you have it but not necessary). My formula is: I use the Dash spoons which are 1/8 tsp. Mix 1 dash corn starch and 1 dash diatomaceous earth melted in 20 drops of distilled water. To this add one plastic picnic spoon full of varnish. Mix all well and you may need to add a few more drops of distilled water to get the consistency you prefer. I ended up adding 10 more drops of distilled water to my mix.
If you are just using the Corn starch use this formula: 20 drops distilled water, 2 level Dash Spoons (or 1/4 tsp.) Corn Starch + 1 level disposable plastic picnic spoon of varnish. Melt Corn Starch in water first then add the spoon of Varnish to it.