MITRA Board - Recent Posts

Answer to: Concentrated UV Light Exposure to Oil Paint

ellie moore — Thu, 09 Apr 2026 07:18:06 +0000

Thank you so much for your reply, Lussh! I hadn't thought about using a varnish with a UV protector first. All the best to you, Ellie

Answer to: Concentrated UV Light Exposure to Oil Paint

Lussh — Thu, 19 Feb 2026 17:32:12 +0000

Hello Ellie,

365nm for 20 minutes shouldn't damage much. It's not the harsher side of UV and I would be surprised if you get any chalking or fading (unless you used dyes).
However since it's dried rather well, you could use a standard solvent based varnish to seal the picture layer and protect it from what will follow.
If varnished on a dry day, you won't have any environmental issue afterward. Some varnishes have some UV protectors I believe.

and since the substrate is rather inert and static, not much to expect for a long while.
These UV cured polymers will give you a better hardness and chemical resiliency than typical artist varnishes as a second layer.

You should have something nice.

Good art to you,

Concentrated UV Light Exposure to Oil Paint

ellie moore — Thu, 19 Feb 2026 13:35:09 +0000

Hi all, my query is about exposing a 6-month old oil painting to concentrated UV light; I’ve made some tiny oil paintings to fit into rings for a jewellery brand, and found out the jeweller will be sealing the crystal cover on with UV-curing glue to make them watertight; which entails bathing the piece in 365nw UV light for ‘5-20 minutes’ to cure the glue. Which is concerning! Is this likely to cause serious problems, either visual changes or to the integrity of the painting, or would they likely be very minor? I know 365nw UV light is used in conservation to examine paintings, but these are only 6 months old.

They are 1.3cm high and very detailed, so a visual change would be the most impactful, although I’ve used pigments with good lightfastness. We will be testing for immediate visual change, but I'm concerned about the paint film integrity in the longer term.

The painting is oil on solid gold, medium Gamsol, Galkyd and Linseed oil, prepared with a lead alkyd ground, 6 months cured, unvarnished, with an air gap between the glass.

Additionally...would a watertight seal cause any problems with creating a microclimate, assuming the ring was assembled during moderate atmospheric humidity? It would seem there’s nothing to create condensation, or mould growth, but I’d love your expert opinion! The whole ring including the painting support is solid 18 or 22ct rose gold, so largely inert.

Thanks so much for your time, I really appreciate it!

Ellie

RE: Comparing Varnish Resins for Oil on Metal Jewellery Pieces

ellie moore — Thu, 19 Feb 2026 13:20:58 +0000

@lussh Thank you for your reply, Lussh - sorry I didn't see it before! Sadly epoxy resin isn't an option for us this time as it's non-removable.

Slightly acidic glue a major problem in home-made linen panel?

JenKyk — Wed, 21 Jan 2026 23:23:10 +0000

Dear MITRA I purchased glue I thought was acid free to make a few linen panels. It turned out I'd gotten the right brand but the wrong subtype of glue. I measured the pH of the glue (Gorilla wood glue, a PVA-based adhesive) with a pH stick and got a reading of 4. I also checked my linen and got a reading of 5, which surprised me as I'd wrongly assumed linen was acid-free, essentially. I won't use this glue again but have one panel I already started a painting on and with my bad painting luck, I won't be able to recreate what I've done easily on a new panel as it depends on the initial oil sketch going well (it's in the lap of the gods, as they say). Should I throw it out or might it have a hope of surviving with that particular pH of glue having been used on good, reasonably thick linen (Claessens loomstate, medium texture, 275 gsm) attached to masonite?

Starting an Oil Painting at Low Humidity

drawingsbyjack — Mon, 15 Dec 2025 18:39:08 +0000

Hello everyone, I hope you're having a fantastic Monday :)

I have a question about an oil painting I've started. I painted a thin layer on a lead primed aluminum panel about a week ago. I wanted the layer to fully cure before continuing, but the ambient humidity has been low, between 28-20%. The temperature is already carefully controlled, at least now, but I wanted to ask about this humidity. I am trying to slowly raise it to 45% over the next 8 days. In the time since I began has any kind of damage begun? I haven't noticed any but I'm asking because I suspect this kind of damage can't be seen right now

The only other relevant information (I think) is that the studio is between 18-24 celcius/75-64 Fahrenheit, and it could drop to the low-mid 50's while I was away for my work shifts during the week (it would naturally be raised back up to a good temperature over another few hours) but those swings won't happen anymore, the temperature will remain stable and the humidity will now slowly rise and stay at a good range.

Do I have anything to worry about?

Answer to: Signing paintings— best practices?

Lussh — Sun, 14 Dec 2025 10:46:02 +0000

Hello there,

Signing there is a humble choice in my opinion too.

If you sign using your colours while painting, with a subtly different tone shift, it can be discreet and a solid part of the painting holding even under varnish. Something near invisible unless one knows where to look along the edges of the canvas or frame. From what you're telling, I think that's the best option.

If it's on the back of a light cloth with thin colouring, pretty much anything will become a bit see through. So there too, best to sign along the folds of the canvas over the wooden frame. Acrylic markers can be of varying qualities, but the risks of bleeding through should be low. Lightfast pens use pigments but the binder can risk bleeding through a bit as well.

Avoid weird chemistries based on oil or wax.

Cheers,

Answer to: Comparing Varnish Resins for Oil on Metal Jewellery Pieces

Lussh — Sun, 14 Dec 2025 10:28:51 +0000

Hello there,

At this point what you would need is "resin" handicraft, aka epoxy and hardener. That will be what holds best against constant friction for a long while, and can sustain water, perfume and more.

Cheers

Answer to: Seeking Advice on Stabilizing Dead Sea Water Paintings

Lussh — Sun, 14 Dec 2025 10:26:25 +0000

Hello there,

I'm probably a bit late, but if I understand correctly, you're not using any kind of glue or medium to bind the pigments to the cloth. If that is so, yes, it will always rub off easily and "live" with humidity. If you want to preserve your art, you'd need to soak it in a binder or another. A varnish would be a start but colours on your favourite media instead of raw pigments would also help a lot.

Good luck and cheers,

Signing paintings— best practices?

mulberry2 — Sun, 14 Dec 2025 04:09:24 +0000

I cannot decide how and where to sign my oil paintings. Each option seems problematic in some way. I am seeking advice, comments, ideas.

I will sign them on the back, and most are on acrylic-primed linen. My paintings tend to be light in color and are frequently thinly painted. So to prevent show-through of any kind, I think I will sign the edge of the linen near the staples. Is this acceptable for long-term authentication? Or do you have other suggestions for almost-white paintings?

I have considered the following mediums, but each have drawbacks.

Pencil: is it permanent enough? Might it rub off onto another painting if they were ever leaning together unwrapped? is there a way to make pencil more permanent and less likely to rub off?

Acrylic paint markers: I have read that these may not adhere well to acrylic gesso, but I have not tried them.

Lightfast pens, such as Pigma micron: I have found these to smear on gesso sometimes, but maybe they are okay if allowed to dry thorougly. Are they permanent enough? Do they look okay?

I would rather not use a brush to sign, but I would if it is best option.

Are there other types of pens or pencils. People have used that work well?

I welcome any thoughts or ideas.