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View Full Version : Isolating layers of paint, delamination risks


forrie
02-23-2019, 12:58 PM
I have been using liquin, spike oil and walnut alkyd in painting. I prefer to oil out the surface with a thin coating of walnut alkyd for some wet-in-wet work, and I prefer to isolate the layers (after they dry) with something, which I've recently experimented with liquin.

My chosen painting support is DIBOND (aluminum composite) that is first treated with a bonding agent, then gessoed. I do this because I prefer to block-in with acrylic first.

I have been told that this combination my lead to delamination, a term I've never heard of but it sounds horrifying and I need some advice.

The isolated layer (ie: liquin) brings out the colors, but also a smooth/slick surface to start over without risk of disrupting the lower layer (I do this with acrylics, too, with the equivalent materials). As for drying time, if I use walnut alkyd, it seems to take about a week to dry, other thinner layers (ie: details) I use the above materials with will usually dry in a few days as well. But I could be mistaken about "real" drying time.

Anyhow, before I invest more time in creating potential disasters, I hope to get some advice from you all in how to do this properly.

Maxfield Parrish famously isolated his layers, using copal varnish -- but, unfortunately, a lot of his works are now cracked. Although I know liquin can still result in lower paint layers being disturbed if you use a solvent, I had thought this would be ideal.

Help, please! LOL


Thank you,

Forrest

Delofasht
02-23-2019, 02:26 PM
It seems to me that the person(s) who told you that delamination is a concern are referring to the Acrylics underpainting. The rest of the ingredients all seem very compatible, but there has been debate on whether acrylic paints form a surface that is receptive to oil paint over time.

There is a big difference between Acrylic Gesso and Acrylic Paint as you probably know, with the latter having a less solids:polymer ratio. Acrylic polymer doesn't chemically cross link with oil paint, according to all but one source that I have read (the one being unreliable with no scientific data to back up the claim). This means that oil paint can only hang on with mechanical adhesion. Picture a zipper, zip up the zipper the teeth grab and hold fast, take away the teeth on one side of the zipper and nothing short of melting them together is really going to hold the two sides together. In our case, we can't even melt the two sides (Acrylic + Oil Paint) together since there isn't a chemical reaction between them (and we surely do not want to cook our painting, at least I assume as much).

The rest of the materials all seem compatible to me, with the caveat that that liquin isolation layers are very thinly applied and wiped down to just the smallest possible amounts (enough to achieve the effect not enough to be seen as an actual layer in themselves). As for the concern regarding "real" drying time, as long as the current layer is as thick or thin as the layer below it and not a faster drying pigment, you are fine with slow drying on top of slow drying or fast drying on top of fast drying. The trouble comes when one applies Umbers or other paints with Manganese in them anywhere other than in the underpainting (these are the biggest and most common offenders, there are others as well, even my favorite of Prussian blue happens to fall into this category of danger). The results of faster drying over slower drying typically ends up being cracking though, but delamination can occur if the aforementioned lack of mechanical adhesion does exist.

Gigalot
02-23-2019, 02:40 PM
Only Zinc White can delaminate. Acrylic, liquin and walnut derivatives are quite adhesive! :)

forrie
02-23-2019, 02:45 PM
Thanks for your reply!

A fairly famous artist, BROM, has been using acrylic for underpainting for many years; I asked him about this and he said he's not had any problems with this application, of oil over acrylic. I used "sandable" gesso, something I learned the hard way (the other form gums up in clumps on the sander).

Honestly, it's so confusing -- which is why I had avoided oils for years, because of the chemistry and so many different opinions and approaches on how to use the materials.

Maxfield Parrish used very thin glazes, isolated by a copal varnish -- he also used sunlight or heat lamps to "cure" them -- something I am not inclined to do. Indeed, I wonder if MP were alive today, what his choice of materials would be (ie: Liquin, et al).

I think one advantage I have is perhaps the surface I paint on, DIBOND. It's not organic and therefore will not move or do funny things over time.

The piece I'm working on now has a decent layer of liquin over it that I simply used a big brush to apply, I didn't wipe it down. I try to work quickly here, as not only is Liquin apt to become sticky fast, it's NOXIOUS AS HELL lol. I will take your advice to heart and use some kind of cloth to wipe it a big, though I don't want to leave dust/particles behind.

I've seen some other artists sealing their paintings with resin, which creates a thick, smooth surface -- I think that just takes away from the painting, as you can't see brush strokes. I also don't use thick paint applications -- they are almost always thin (ie: no impasto).

I guess time is going to tell, but as I'm still learning.. I want to figure out how to do this correctly.

I've had others tell me to paint in as few layers as possible. For my work, I can't really do that -- for time constraints and just how I approach the work. In acrylics, I always paint a layer of matte/gloss medium over the dried work before proceeding -- brings out the color and protects the layers (ie: thin glazes) from being disturbed.

Delofasht
02-23-2019, 05:11 PM
Well, if your priming had a fair amount of solids then your acrylics on top of that should retain the texture so long as it was thinly painted and not impasto or anything like that. Basically your mechanical adhesion should be maintained by the choice of primer, just to know, Bromís work has been largely for Illustrative purposes or built on the need for speed. His work is fantastic of course, but whether it needs prove the test of time is really not relevant, it need only last his lifetime really.

In short, I would only worry it if you are doing everything in your power to actively destroy your oil paintings. From the descriptions of your methods given I really doubt any of us will be alive to see your works falter, and who knows what could destroy them before their own natural self destruction (nuclear fallout, cannon fire, plasma bolts, diachronic shift, we have no idea what is possible in the next 50 years). So no worries, paint away man!

forrie
02-24-2019, 02:06 PM
LOL Nuclear fallout :)

I agree, we have so many new materials that there really is no real way to tell, apart from time.

My sandable gesso is applied with a couple of coats, but they are thin and I wet sand them after and wipe down; along with the marine bonding agent below, necessary for adhesion to DIBOND (that stuff is noxious). So it should be OK.

Thank you again.