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arbrador 09-12-16 09:30 PM

Untempered Masonite
Hi All~
It used to be easy to find untempered Masonite but now none of my local lumber yards or home depot type stores seem to carry it. Of course the art suppliers carry it but only in small sizes and I need a 4'X8' sheet.

Oddly, my local lumber store has what they call tempered Masonite but it looks like untempered to me ie light in color. I remember tempered Masonite has having a rich, dark oily look to it.

What would be the danger in using this pale-looking tempered Masonite? Theoretically the resins used in making it could migrate through the gesso but I wonder if that would actually happen- even through the centuries. Wood pulp- lignan is very acidic anyway and we don't seem too concerned about it.

Any strong opinions??
BTW, I use 1/8" Masonite (hardboard) and cradle it with moulding glued on the back.
Lora Arbrador

arbrador 11-12-16 05:49 PM

Masonite = fiberboard
I'm going to answer my own questions but hope others jump in. It seems that the Masonite company was bought by a door company and no longer produces fiberboard. Masonite-like products are now called "fiberboard". Particle board is not as dense and should not be used.

Here is an excellent article about fiberboard. It answers a lot of questions and also causes more confusion:

I'll let you know what I find out as I continue research. Please jump in!

arbrador 15-12-16 03:59 PM

fiberboard painting surface
Hi All,
I have been communicating with Ampersand and have learned a great deal more about fiberboard. I'm going to post my correspondence with them as I think it is very edifying. Here goes:

Hello Lora,
Thank you for your interest in Ampersand!
Our panels are tempered. Can you tell me a bit about what you are looking for, and the intended use? I may have some ideas for you.

We do sell full sheets as custom items. If you wanted it cut to size, however, that would likely help reduce the shipping costs of sending a full sheet from us in Central Texas.

We do not offer our Archiva-Seal as a separate item. There are commercially available products that I can recommend to you. GAC 100 from Golden Artist Colors and PVA Size from Gamblin Artists Colors work well as wood sealers for preparing wood for artwork. All of these sealers are polymer-based.

Please let me know if you have any questions.

Kind regards,
Mr. Dana Brown | Customer & Retail Support | Ampersand Art
PO Box 1440 | 1235 S Loop 4 • Ste 400 | Buda, Texas • 78610

Here is my response:
Hello Dana,

Thanks for all this information!
Egg tempera artists generally don't like using tempered fiberboard. Do you have any feelings about it? Also being purists we're probably scared of using any polymer to seal our boards.

I would be interested in obtaining some of your "green" fiberboard but actually I'm planning a huge painting that will take a 4x8 sheet. Would you be willing to share contact info for your source of fiberboard? Perhaps I could find something in California.

I respect the work you do bringing quality panels to us confused artists.

Many thanks,
Lora Arbrador

Here is Dana Brown's response:
Hello Lora,
Good questions! I do have feelings about tempered panels J
The process of tempering fiberboards is not based on an industry-wide standard. The amount of oil used, the type of oil, and the remaining or residual oil (as a result of tempering) varies manufacturer by manufacturer. Our tempered Hardbord is made completely of 100% wood fiber, containing no residual oils from the tempering process. This has been attested to by the conservation scientists at the National Gallery in Washington D.C. While Ralph Meyer’s, “The Artist’s Handbook” continues to go through revisions, the section on fiberboards (referred to as Masonite) hasn’t been updated, and it contains outdated information based on how these panels were made, more than 50 years ago. Here is a link to an article on our site, that goes into more detail: I would still urge caution about using tempered panels from the lumberyard, since they are designed for construction purposes, and the information about the amount or type of oil used is largely not available to the consumer.

Our Hardbord is made to our specifications but is proprietary, so I am unable share our source, unfortunately. We would be able to sell you full sheets, shipping from here in Texas, if you like. There is not a California source for our full sheet panels, as we are the only Ampersand location.

Conservation scientists also caution against the use of animal hide glues for sizing because it absorbs moisture from the air, and becomes brittle over time. They instead recommend pH neutral PVA Size for this process. By working on a panel as you do, that does help to reduce movement of the finished work and its paint film.

Also, egg tempera painters have been using our Claybord since its introduction and more recently, using our Encausticbord as well. Both of these panels have high-solid proportion ground coatings that are quite absorbent. The Claybord surface is polished smooth, while the solids in the Encausticbord ground give it a slight texture and the highest absorbency of any of our surface coatings. I know that the Society of Tempera Painters (and I do understand that you were one of the co-founders) mention on their site that we have previously stated that Claybord is not suitable for egg tempera, but this information is not accurate. We work with many egg tempera painters, who successfully use Claybord for their paintings.

I appreciate that you have contacted me with your questions! The issues about materials, options for artists, and artistic process are all important, and often over-generalized and misunderstood. Thank you for your interest!

Please feel free to let me know if you have any questions.

Kind regards,
Mr. Dana Brown | Customer & Retail Support | Ampersand Art

I do recommend reading the information in the link he gives in his message:

Here is my most recent response to him. I'll let you know if I find out any more.
Hello again Dana,

Thank you very much for your very knowledgable response! Ampersand certainly has put so much research and thought into artists' panels. I am very grateful for that!

I read your information about hardboard and it was very impressive and edifying. It makes total sense.
I would be interesting in knowing the cost of a 4x8 sheet and also what the shipping might cost. It does seem crazy to ship just one sheet of 1/8" fiberboard and it would be prone to breaking unless backed up with something rigid like plywood which would make it even more expensive to ship but perhaps there is a way that is not prohibitive. A trip to Texas with a station wagon perhaps? (lol).

Sealing the panel with acrylic sealer does make sense as you explain it but is still a little scary for us old timey tempera painters. I will try to have an open mind and share the info with the Egg Tempera Forum and hear their response.

As for Claybord, unless you've changed the formulation from the beginning, I did not find it absorbent enough for Egg Tempera. I had very high hopes for it but, as I recall, the paint seemed to pool on the surface and then pick up. It was not pleasant to work on as is chalk/rabbitskin glue gesso. It's OK for someone just starting out and wanting to play around a little with ET but once someone starts to really explore the medium it's my opinion that traditional gesso is a better match. As for the Encausticbord it sounds more absorbent which is good but does it have a rough surface? Many of us ET artists do like the smooth surface.

So back to the hardboard. Please do let me know the price as you do have me convinced that your hardboard it the way to go.

Many thanks for your expertise and well-articulated explanations,

Lora Arbrador

arbrador 21-12-16 04:21 PM

more on hardboarad
I should have checked previously but now see that True Gesso has a very thorough analysis of the hardboard industry and their conclusion is that these two brands are the most appropriate for our uses.

Two boards have survived our analysis:

1) Louisiana-Pacific’s“Premium,Untempered Hardboard,”which is the original Abitibi-Price product now made in the original plant by DPI.

2)MasoniteInternational’s untempered or “RegularDuron”,made in Danville,Virginia,the original name but much-changed and refined over the years.

Here is the entire article:

But this was written/edited in 2003-8 so thing may have changed. I may contact them and ask what they are using these days.
But the problem is even if the ideal hardboard is located, to buy a single 4'x8' sheet would be prohibitive to ship even if it were available in single sheet. Most ET artists paint small so they can order small panels from Ampersand or True Gesso but I am planning a 3'x8' painting for which I'll need a whole sheet.

Any thoughts?

Koo Schadler 22-12-16 06:23 PM

Hi Lora,

Yes, that article is quite dated. It was not written by the current owner of True Gesso but by Eric Thomson, who started True Gesso in 2003 (which is approximately when he researched the information presented in the article). It's very hard to keep up with the "engineered wood panel" (as fiberboards and plywoods are known) industry because products are made all over the world, from differing standards, and materials and processes are always evolving. I'll post a generalized update of what I know, and hopefully that will be helpful.


Koo Schadler 22-12-16 06:45 PM

Hello Lora,

A 4 x 8’ panel is about a five years worth of paintings for me! I admire your stamina and sense of adventure.

You raise many good points in your postings and I have several ideas to chime in.

Although there are many variables that can affect the durability of a work of art, in general an engineered wood panel is probably preferable (longer-lasting) than a solid wood panel. There are essentially two types of engineered wood panels: fiberboards and plywoods. Already this is going to be a long post, so I’ll just address fiberboards.

All “fiberboards” are made from wood that has been chopped into a gazillion pieces (lignocellulosic fibers), then bound together under heat and pressure, sometimes with added oils or resins. The industry is always changing, but as of this writing there are three types:

1. UNTEMPERED HARDBOARD, made from wood fibers alone (natural lignins in wood hold the board together, akin to making paper).

2. TEMPERED HARDBOARD, same as above but with a layer of oil or alkyd applied to the surface to increase strength.

3. FIBERBOARDS made from wood fibers, synthetic resin and a small bit of wax. There are three kinds: Particleboard, MDF (Medium Density Fiberboard) and HDF (High Density Fiberboard).

For decades un-tempered hardboard (including the brand name Masonite which, as you note, is no longer produced) was recommended for tempera artists. Tempered boards raised two concerns:

1. The oil layer on top might migrate up to the gesso and paint. In fact, the oil layer is cured and not able to migrate, so this is not an issue.

2. Traditional gesso does not adhere as well to tempered board. This concern is legitimate, especially in the early days when the oil layer was significant. Less oil is used now to temper boards, but still adhesion of traditional gesso is not as good to tempered versus untempered board.

However adhesion is not necessarily so compromised that tempered boards should not be used. Whether to use tempered board is dependent on many variables: how much oil is applied, how diligently the board is prepped before gessoing, what conditions the artwork is kept in, importance of durability to the artist, etc. It’s a personal decision. Suffice to say that tempered boards are a bit stronger, but adhesion of traditional gesso is not quite as good; untempered boards aren’t quite as strong, but adhesion is better.

(An aside: Wherever I comment on adhesion, I’ve tested it using a “cross hatch adhesion test”; explains the test.)

The controversy concerning tempered versus untempered is becoming moot because it’s increasingly difficult to find untempered hardboard (the great majority of fiberboards are used in the construction industry, which has little use for untempered board). Most lumberyards now stock only the fiberboards mentioned above: Particleboard, MDF and HDF.

Particleboard is low quality, low-density and not recommended. HDF is the densest and most stable, but heavy and not commonly stocked (although it can be ordered from most lumberyards). MDF is readily available, pretty strong, and a good option. The resin in the boards is cured and does not migrate. And because the boards are about 80% or higher wood content, the surface is still fairly absorbent, which allows for mechanical adhesion. The adhesion between MDF and traditional gesso was good when I did a crosshatch test.

Urea-formaldehyde in some resins is a potential concern. Low levels of formaldehyde occur naturally in wood, so no wood-based panel is formaldehyde free. But added formaldehyde can cause off-gassing and health problems to painter and painting. In recent years there’s been an effort to curb formaldehyde in fiberboard (as well as plywood) and most engineered wood products now meet “CARB” (California Air Resources Board’s) emission levels. Whatever engineered wood panel you choose, look for a CARB seal of approval.

Regarding Ampersand’s hardboard – as Dana says, it’s very well made and recommended (see this article, If the price proves too steep, I would say you’re okay using a MDF panel. If you can, find out where the panel is made (not always easy) and opt for US production – overseas, engineered wood panels may be made from inferior ingredients and/or not meet CARB standards.

The purpose of priming is not to block migration of oils or resins– as mentioned, those substances cure and don’t migrate. There are two reasons to prime:

1. To help with adhesion of the ground. A primer is an intermediary between the wood panel and gesso.

2. To block “support induced discoloration”, or SID. When water-based paints are applied to wood panels, the water can cause tannins and other contaminants in the wood to draw up into the gesso, slightly darkening the ground. SID is a relatively new concept, first studied in the 90s by Golden Paints in relation to acrylics. It hasn’t really been studied or addressed in egg tempera as far as I know. There are various products for blocking SID (Archiva-seal, GAC 100, PVA), as Dana mentions. The problem is that they are all polymer-based and designed to sit under acrylic or oil grounds, not traditional gesso. I tried a crosshatch adhesion test of traditional gesso atop GAC 100 and adhesion was not good.

I also tested to see if SID even occurred in traditional gesso on a MDF panel (how to test for SID test is described at the Golden Paint website). In my limited testing, very little to no SID appeared. This may be because of the high “solid content” (percentage of chalk) in traditional gesso, or low contaminants in the MDF board I used – I don’t know. So the concern of SID in traditional gesso and egg tempera is more theoretical than practical at this point. Until SID is better studied or demonstrated in traditional gesso and egg tempera it’s hard to say whether or not priming a panel to prevent SID in tempera is necessary; or, if it is necessary, what primer to use (since traditional gesso doesn’t adhere as well to polymers). If this long paragraph on SID seems a tangent, I mention it only because your discussion with Dana brought up polymer-based primers. The ones he mentions are all excellent products under acrylic and oil grounds (Clayboard is a polymer-based ground), but are neither compatible with nor possibly relevant to traditional gesso.

Animal glue (generally rabbit skin) is the traditional primer under traditional gesso (not to block SID, if SID even occurs in traditional gesso & ET; but as an intermediary layer between wood and gesso). The adhesion between wood-based panels, animal glue, and traditional gesso is excellent. As Dana correctly states, animal glue has downsides. It grows brittle with age; but then again, so do egg tempera and traditional gesso (which is why tempera artists should work on panels). Animal glue also is hygroscopic - attracts moisture - and moisture is one of the most detrimental elements to the long-term health of a painting. However many layers of cured, polymerized egg tempera paint on the front of a painting seal, to a fair degree, underlying layers from moisture – so it’s questionable how much moisture is actually drawn to a thin layer of animal glue primer under many layers of traditional gesso and cured egg tempera paint.

The greatest concern for moisture entering a painting is via the sides and back of a panel, particularly if those areas are wood-based and unsealed. One of the most protective things you can do for a painting is to coat the sides and back with a couple of layers of alkyd house paint (solvent-based alkyds preferable to water-based, available at any hardware store). I would say this step (not often mentioned) is much more important than avoiding an animal glue primer.

Koo Schadler 22-12-16 06:46 PM


Finally, I’ll comment (as I have in other postings) on Dana’s claim that Clayboard is suitable for egg tempera. He is correct that egg tempera can be painted on Clayboard and there are tempera artists who use it. But what you, I and scores of other egg tempera artists know is that Clayboard does not give optimal working properties to egg tempera. I have tested it many times and say with confidence that tempera paint has a greater tendency to slip and lift on Clayboard. Ampersand, the company that makes Clayboard, understands this, which is why they post special instructions for how to work with tempera on Clayboard in order to get the paint to behave. There are no special steps required with egg tempera on traditional gesso – the paint behaves beautifully.

Egg tempera is already a challenging medium (make paint from scratch, build images slowly, etc); and beginners can become discouraged if they experience problems while working on Clayboard (advertised as “great” for tempera) - they tend to blame themselves or the medium, when in fact the ground may be at fault. I appreciate Ampersands extremely well made hardboard panels, and Clayboard is an excellent product for certain mediums and working methods. But promoting Clayboard as a “great” option for egg tempera is a bit like encouraging oil painters to work on watercolor paper. Yes, it can be done, and if a painter has not tried any other surface he or she may think it works fine, and some oil artists might prefer or even thrive on an alternative surface. But most oil painters want to work on a ground that optimizes, not limits, the properties of their paint. Tempera artists deserve no less - an optimal surface for their paint.

(If there are tempera artists who think me too biased, I suggest they paint several temperas on a good, traditional gesso ground, then paint an equivalent work on Clayboard. In my experience the majority become enthusiastic converts to traditional gesso. And whatever the questions regarding the durability of traditional gesso, there also are durability questions regarding polymer grounds under tempera. Never mind that there is a centuries old, generally successful history of tempera on traditional gesso.)

As always, thanks to the STP community for putting up with my long posts, and I welcome comments, corrections, input of any sort.


arbrador 23-12-16 04:12 AM

More on panels for ET
Hi Koo!

I'm grateful for your long and detailed posts. I would be disappointed in anything less!

I've been using already gessoed panels from True Gesso and thus have not confronted the changing world of panels for many years. BTW, since the Thompson article is out-of-date and I didn't see any info on the site I am wondering what True Gesso is using for a substrate these days?

On tempering, from the conversations I've had with hardboard manufacturer's (Mainly Stimson in Oregon), I've found that sometimes a panel is called tempering without any oil at all. Just more pressure is used to "temper" the panel. But in any case it seems much less oil is used than prior methods as you mentioned. I've also been encouraged to hear that the formaldehyde is on the way out in many products that have a more "green" orientation.

Per your recommendation for MDF, I've been looking for 1/8" MDF and it does not seem readily available perhaps because it is not dense enough to be made in 1/8" thickness? Because I am working so large I need the board to be light so that with the cradling it won't be ridiculously heavy.

So probably back to hardboard for me. I think I can find something reasonable or at least I hope so. It will need to be relatively local or the shipping will be untenable.

On the Alkyd house paint I'm wondering if that would disrupt the balance of applying equal coats of gesso on front and back? Or perhaps that is not as important when a panel is cradled? I'm considering a hardboard that is S!S (smooth one side) and therefore has the screen pattern on the rear. That was always challenging for gessoing as the screen back gobbled up a lot of gesso. But the S2S hardboard in my area looks inferior in other ways.

I totally agree about Clayboard and ET and you articulated it so well! I think I will refer Dana to our forum so he can read your post. He seems like such an informed and ethical person so hopefully he will convey our concerns to his superiors in the company.

Let me know if you have other thoughts. Guess we're lucky that most of us are not using planks of hardwood anymore and having to deal with the joints. But they sure painted magnificent paintings on those panels and are letting the conservators deal with outcomes.


Koo Schadler 26-12-16 07:42 PM

Hello Again,

A few more points...

I've talked to a couple paint experts about SID and egg tempera. They agree that, barring further tests that shows otherwise, SID is not a great concern in tempera. So you can cross that one off the list (which you never put there, but came up in regards to Clayboard).

When the person at Stimson says boards are being "tempered" with additional pressure, it's not a useful way to describe the process, as it confuses what has been the meaning of "tempered" in regards to hardboard; i.e. a layer of oil on top. Confusing terminology is common when discussing hard- and fiberboards. With due respect to the helpful person at Home Depot who is making minimal wage, employees may or may not be more or less informed about an admittedly complex, every-changing industry (hence the persistence of the word "Masonite" to describe fiberboards in general, even though the company no longer exists and the word "Masonite" doesn't have a specific meaning).

In other words, if you want to know what's in a hardboard panel, you have to be well-informed yourself to know what questions to ask. Be persistent too, as most customers don't need to know as much as a painter hoping for longevity in a panel, and lumberyards aren't necessarily accustomed to being grilled on the ingredients and quality of panels (more than once I've been told, "Now missy, that 'masonite' panel will work just fine...")

One solution is to buy a hardboard panel made specifically for artists. There are two I know of: Ampersand's Hardboard, mentioned previously (probably the best quality option) and Art Boards. I'm not recommending the polymer-based grounds that these companies make and advertise as suitable for egg tempera. I've tried them both and the paint slips, slides and lifts. But I do recommend their panels, which are well-made and designed for artists (whereas the fiberboard in the lumberyard is made for the building trade and not made to last as long as paintings are supposed to). However not everyone can afford Ampersand's or Art Board's products. If you must use a lumberyard panel, try to find out where it's made (as mentioned, preferably in the US), the ingredients, and be diligent in your preparations and gessoing. (Also, label the back of a painting with ingredients involved in it's making, so if future restoration is needed the conservator knows what he or she is dealing with).

Plywood is another, and perhaps better option, as it's a bit easier to get good quality, find out what the ingredients are, and they are fairly stable and dense. Plywood panels should be coated with cloth before gessoing, which is more work, and are heavier, so they are not for everyone.

Regarding how to balance the coatings on front and back of a panel - you are right, it is an important consideration. If you prefer to use S1S (smooth one side) board, with a screen pattern on the back (which creates more surface area and thus takes more gesso and/or house paint to cover) you have to approximate equivalent coatings on both sides, which is tricky. I prefer S2S (smooth two sides). I apply equal coats of gesso front and back, two coats alkyd house paint on back, then build up tempera paint on front. In the end a hundred thin layers of tempera are more or less equivalent to what's on the back, I hope, but it is admittedly an approximation.

Coating the back and sides with alkyd paint is important regardless of a cradle, to protect against moisture. Cradles themselves are problematic - they inhibit warping and are requisite on very large panels like you work on (to keep it from flexing). On the other hand, wood braces want to expand and contract with changing humidity, and if glued tight to a panel and thus prevented from moving, stresses in the braces travel up into paint layers, which can lead to cracking and delamination. A layer of cloth atop a panel will absorb some of this stress.

Not everyone cares about longevity in a painting, but if you do there are no easy answers to how to build a complex, many layered construction of varying materials and get it to last for centuries under unpredictable, at some point probably adverse, environmental conditions. I know, "that's what museums and conservators are for" - but in fact very few paintings end up in the hands of a museum or good conservator. So you are right to take care when making your beautiful and impressively large temperas.


arbrador 07-01-17 10:13 PM

More on hardboard and cradling (bracing)
Hi Koo~
Thank you for your thoughts on panel cradling. I hadn't thought about how the cradle itself could cause problems. I suppose I should glue on canvas before gessoing. I do worry about the canvas lifting off but I know some icon painters use it and it would be an extra protection. I seem to remember one glues the canvas on with the same size used to seal the panels. Hopefully I can buy canvas large enough so that there are no seams to worry about!
I'm also going to be more careful about buying kiln-dried moulding strips so that there is minimal shrinkage of the wood as it dries. One year I made my own wood glue from casein and lime and it is very strong but I've since just opted for regular 'ol Titebond and clamps. The edges are always an issue. Of course I chamfer them but it is still a vulnerable point.
As always thanks so so much for your incredible knowledge and willingness to share!

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