Home Forums Explore Media Oil Painting The Technical Forum Lesson Learnt – MDF prep for oil painting

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  • #457311
    bhindi
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        In recent months, I have been devoting some time to learnt the craft of wood panel preparation for direct painting. There are two types of boards I can use easily – MDF and plywood (all thickness available). I got a few pieces – 6mm MDF (13″x16″) and one 10mm plywood piece (10″x12″) to try. I understand there are a few steps to prep such boards:
        1. Sand surface lightly
        2. Use of some kind of sealant on the surface – shellac, lacquer or polyurethane. The hardware shops near where I live – maybe 10 of them – all only had a lacquer sealant so that’s what I had to use.
        3. Gesso two coats at least on the surface.
        4. Paint away?

        When I got the lacquer sealant, I didn’t know in what quantity to dilute it. The hardware store told me to add about 10-20% solvent to make it workable. So that’s what I did. This was 3 weeks ago. Clearly, the surface was much too smooth and was not sanded after the sealant application. It did not adhere to the gesso. I saw only yesterday that it peeled right off the surface. On the other hand, a week after I had prepared the MDF boards, I read some more and found that I could dilute the sealant with 50% or more solvent, and apply two coats, if necessary. I did that on the plywood and there is no adhesion problem with the gesso on it.

        I am a little disappointed, but I am determined to make the MDF panel work. I believe what I need to do is to peel off the gesso and then sand the surface and reapply. But then again, maybe I’ve got all this completely wrong. Any advice?

        #638157
        Ellis Ammons
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            If you are looking for something cheap, Bullseye 123 works well to size the mdf. The general artist recommendations are Rabbit Skin Glue, PVA glue, or my advice GAC100.

            Side note W&N told me no hardboard is archival. I’m a bit skeptical however. I would think hardboard to be archival if it’s just made with ground wood pulp and linseed oil.

            Check out my work in the acrylics Hall of Fame Camellia WIP
            oil and acrylic paintings..

            #638156
            kinasi
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                Why would you use lacquer for a painting. It’s a finish for furniture, not paintings, gesso isn’t going to stick to it. Use something like GAC.

                No one knows if MDF will last, it has nothing to do with wood panels that lasted, those were from solid wood. MDF is small fibers and formaldehyde, who knows if that will last. Formaldehyde escapes over time, that’s why MDF smells and why the furniture aisle in Ikea smells.

                #638161
                Tom Murray
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                    I don’t recommend this but:
                    In the late 70’s I was making very detailed mandala paintings on masonite.
                    I started with tempered masonite and applied about 9 thin coats of gesso (not acrylic) sanding each coat smooth.
                    I still have most of those paintings and they look exactly as they did the day they were finished.

                    #638149
                    Gigalot
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                        Laquer is not a good sealant to bond with Acrylic. It can be used to bond with oil paint. I can recommend to seal MDF panel with warm gelatin gel. Take gel, not a liquid and spread it on the MDF surface with large palette knife or with hand. Try to control how it lays to avoid beading. Apply one or two coats of gelatin for the best result. Let it dry and then apply acrylic primer on top of it. Acrylic bonds to gelatin much better than to any other surface, except fibrous canvas.

                        #638164
                        bhindi
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                            I should have mentioned that US brand name sealants are not workable for me as they have to be ordered online at greater than double the original cost because of import duty. I live in India.
                            Kinasi – I read that there are 3 types of wood sealant – shellac, lacquer and polyurethane. At all the woodworking places I went to, they all use only this one lacquer finish and they all call it a sealant. I suppose it is because it worked well and so the gesso did not adhere.
                            Gigalot, gelatin gel? They are only available as some kind of vitamin capsule here. Lol.
                            So, sanding this lacquer surface and applying gesso will not help? I will try that with one.

                            Ellis, you mentioned PVA. The widely available glue here is Fevicol:
                            https://www.amazon.in/Pidilite-DHR_087-Fevicol-Synthetic-Adhesive/dp/B016MMV39G
                            I wonder if I can use this as a sealant?

                            About MDF – it may not be the BEST option, but I want to try.

                            #638150
                            Gigalot
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                                Gigalot, gelatin gel? They are only available as some kind of vitamin capsule here. Lol.

                                Put one tea spoon of gelatin flakes into 100 ml warm water to swelling. Let it stay 2 hours. Then heat it carefully until gelatin dissolves into water and form solution.
                                Then cool this solution. After cooling, put the solution into freezer and control when soft light gel appears. Do not freeze it until strong marmalade. :) Then put some pieces of gelatin light gel on the MDF surface and rub it into until light thin coat of it will cover whole surface. Then let it dry overnight. And, finally apply acrylic gesso on top. Acrylic will adhere more than perfectly. Let acrylic dry at least one week to make coalescence between acrylic polymer particles to form stable acrylic layer and to remove excessive moisture content from whole MDF body. Then you can paint with oils on top of it.

                                I don’t understand why you need advertised adhesives with unknown formulation? You can do what 90% of Russian artists did for centuries. Take hide glue to seal large MDF panels or just use odorless gelatin for smaller panels. :confused: Are you sure you really need something unknown and expensive material? If you can’t get gelatin or hide glue, then Carboxymethylcellulose glue for wallpapers can be useful. I had never used it for sizing, but it is cheap water soluble strong glue for general purpose domestic works. :angel: Or, at least, take a water soluble transparent glue tube from supermarket. It contains 30-50 ml of strong water soluble synthetic Chinese resin to use at school and kindergartens as a non-toxic paper glue.

                                #638165
                                bhindi
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                                    Ok… Sanding and reapplying gesso did not work. It can be scraped off easily with a pencil.

                                    As far as need – I don’t know what I need. I’m trying to understand. I can work on getting my hands on gelatin and giving that a go. I will also try the Fevicol. It is a brand, but a commonly and economically available one.

                                    Gigalot, you are talking about animal hide glue in INDIA? Before you know it, there will be protests calling for ahimsa art!

                                    #638151
                                    Gigalot
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                                        Gigalot, you are talking about animal hide glue in INDIA? Before you know it, there will be protests calling for ahimsa art!

                                        Ok, but that is not a problem. As you need is WATERSOLUBLE glue to make a BONDING layer to WATERBORNE ACRYLIC upperlayer. Gum arabica, resinous sap from almond and plum trees, methylcellulose derivative synthetic glue, watersoluble sodium salt of polymerized acrylic acid. Guar gum, also called guaran is also water soluble glue.

                                        #638146
                                        wal_t
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                                            Just a question, is there anything wrong with not using a glue/size as preparation but just sand the mdf or hardboard panel and apply a few layers of acrylic primer ? Walter

                                            #638158
                                            Ellis Ammons
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                                                This bullseye is very good and easy. I would use it if I was just doing painting for prints or non-archival work.. Chances are it will probably outlast the oil paint anyway.. https://www.amazon.in/Rust-Oleum-Bulls-Water-Base-Primer-Sealer-Killer/dp/B000SKU8VI/ref=sr_1_3?s=industrial&ie=UTF8&qid=1528708213&sr=8-3&keywords=acrylic+primer+sealer

                                                Again if I was going for something archival I would just paint on natural wood sealed with GAC100.

                                                Check out my work in the acrylics Hall of Fame Camellia WIP
                                                oil and acrylic paintings..

                                                #638166
                                                bhindi
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                                                    I am curious.. why did the lacquer sealer work on the plywood? Maybe because I thinned it more? The gesso does not scrape or peel off that surface.

                                                    wal_t – I understand that the surface must be sealed otherwise, there is risk of substances from the wood coming to the surface and discoloring/damaging the gesso. I may be wrong. Maybe someone can explain.

                                                    #638167
                                                    bhindi
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                                                        update: nothing works. mdf is stupid.

                                                        #638152
                                                        Gigalot
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                                                            update: nothing works. mdf is stupid.

                                                            Proper bonder for acrylic primer is a polymer, that can dissolve partially in acrylic primer. That makes a complete molecular intermixing into the border layers between acrylic upper layer and soluble polymer glue in underlayer. However, if support is completely hydrophobic, then do not use water soluble glue for priming and do not use acrylic primer. Just use hydrophobic sealant and oil-based primer.

                                                            #638162
                                                            ecar
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                                                                MDF + 3 coats of Lefranc Bourgeois Gesso = NO trouble
                                                                https://www.geant-beaux-arts.fr/gesso-lefranc-bourgeois.html

                                                                Eric

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