View Full Version : a question on isolation coats and mediums

10-26-2004, 10:20 AM
I have just been reading the posting on Golden acrylics refering to mediums and isolation coats. Could someone explain to me what an isolation coat is please?
I do acrylics after so many oils, and love the medium, though they are terribly frustrating to use after the leisurely application that oils present. I note that some advocate the use of mediums, more than the use of water, Jaxas for example? One problem I have, using mainly Golden acrylics, is they dry as soon as they are put onto the surface, their workability is very strictly limted. Should I be using more mediums, I use the gel and the polymer a lot, with water, but wonder if there is something i am missing, or is it lack of practice, I wonder.
Any thoughts on this would be greatly appreciated.

10-26-2004, 01:37 PM
You can add a bit of gel, fluid, or liquid retarder to your paints when you first mix them up. Or, try a slow-drying glazing or blending medium, which already contains retarder. Then, spritz your paints occasionally with water to keep them moist. Spritzing the canvas just before you lay on the paint is sometimes helpful, depending on the thickness and blendability you are after.


10-27-2004, 02:38 AM
As I understand it, an isolation coat is a layer of medium usually applied over a finished painting prior to varnishing. This way, if the varnish is ever removed there's less chance of damaging the original paint layers.

However you can also paint directly atop such isolation coats and this (combined with everything dspinks mentioned) is one way to extend drying time. If your painting atop gesso at the start of your painting, it is absorbing water from your paint. Painting atop medium lessens this.

I have lately been isolating each transparent glaze for various reasons and having success.

- Matthew Durante

10-28-2004, 04:23 AM
Hi Nick, Matthew's summary of an isolation coat is right on the money.

If you have consistent struggles with acrylics and their drying time it's certainly worth exploring a few mediums to see how they'll work for you. Golden make the best selection and they're fairly widely available in the UK; their website will give you a rundown of the characteristics.

I started with acrylics using fluid medium and retarder all the time but now I use only water usually because it suits the way I paint and how I want the surface to look - generally speaking acrylics will level better when thinned with water only and I usually aim for zero texture. They also airbrush most consistently if you use only water. Additionally I frankly prefer the feel of the paint thinned with just water when you're applying it thinly, it's far less likely to become clingy than if you thin with acrylic medium or a mix of medium and water; this is one of the main reasons I switched to using water by itself in the first place.


10-28-2004, 05:28 AM
I use fluid medium too, but because I want to extend my paint more than keep it from drying. I have retarder (liquid kind in a drop bottle) for the summer. I'd recommend having a look at Golden's site (www.goldenpaints.com) on the pages all about mediums - they tell you exactly what each one does. Look for those that extend drying time. :) Like the others mentioned, they're usually glazing mediums or retarders. (With the Golden products they all say it on the labels too.)