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I am making some shadow boxes for a project. MDF seems great, but the texture of seams and different orientations of the grain shows through the finish. It was sealed with shellac.
This try at finish is rattle can black. I notice that where glue was smeared, that seemed to work well, but before I smear glue on everything, I am checking for other ideas. I cannot use epoxy due to extreme allergy.

Is the rattlecan acrylic, enamel, or something else? Maybe a couple coats of a rattlecan primer first?

If I remember right you can use spackle

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Jim Watts
http://jameswattsguitars.com

The product is Krylon Color Maxx Paint/primer.

Back in my model shop days we used Bondo to cover MDF seams. If you can't be around epoxy l don't know how much better Bondo would be.

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Stay with the happy people.
--Reynolds Large

I am OK with Bondo--totally different chemicals. I used Bondo on the gaps, but it is a bigger problem. The "end" grain on the MDF is a different texture. Smeared glue, though sanded down, is smoother than everything else under the paint. I will try the various suggestions.

Watch out for anything water-based on the "end grain". It can cause swelling.

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formerly known around here as burbank
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http://www.patfosterguitars.com

We also used some sort of filler that looked like green toothpaste and came in a similar style tube. This was for end grain and pinholes. All the MDF was primed with a heavy bodied gray automotive primer.

_________________
Stay with the happy people.
--Reynolds Large

the core of MDF has always been a painter's nightmare...unlike the outer layer it's very porous and soaks up finishes like a sponge...by outer layer I mean when MDF is in its manufactured state of equal thickness (whatever that may be) where the outer layer appears to have been rolled to thickness and hardened by said procedure...back in the day I remember profiled mouldings made out of MDF that were supplied unprimed (these days it's very rare to see it not being factory primed)...in the case of let's say door casing in let's say colonial style it's all core material and fuzzy as all hell...either way getting that porous core sealed to the point it doesn't absorb anything is essential along with sanding it smooth before the final coat if one wants a smooth surface...I rather like your idea of wood glue being rubbed into it as that seems like an eloquent, if not messy, solution

I tried using MDF once to make a vacuum fixture. That smooth, shiny surface only looked airtight. It was useless in that application.