Using a piece of unpainted MDF in the attic as a shelf

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neb

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#315480 20-Jul-2024 18:38

I need to site some electronics up in the attic and have a length of MDF left over from another project that'd be just about right, but I'm wondering about the advisability of putting it up there without a few coats of paint first to seal it. The attic isn't terribly damp, in fact for most of the summer it's baked bone dry, but then MDF has problems with moisture so I'm wondering whether I should go through the hassle of painting (multiple coats since the first few will soak in) before putting it up there. Any thoughts?

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#3261906 20-Jul-2024 19:14

Unless it is likely to get damp, wouldn't worry. I'd be more worried about the heat killing the electonics in summer.

neb

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#3261908 20-Jul-2024 19:34

It doesn't actually get that hot up there, and I'm using industrial-grade stuff which shouldn't be worried about it anyway.

timmmay

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#3261915 20-Jul-2024 20:15

If something goes wrong you can always buy another piece of wood relatively cheaply. You don't have a lot to lose giving it a go I'd have thought.

Any thoughts @mdf?

Gordy7

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#3261922 20-Jul-2024 20:42

The MDF shelf in the attic... all depends on the value of your electronics and whether appearance is important.

Multiple coats of paint seems a bit excessive and will take a lot of time.

My first quick option is to use a lacquer sanding sealer... good penetration and quick drying.

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neb

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#3261925 20-Jul-2024 20:58

Gordy7:My first quick option is to use a lacquer sanding sealer... good penetration and quick drying.

Yeah, that'd be the ideal option, my reason for defaulting to (acrylic) paint was that I still have a pile of that left over from the house redo and it's water-based and easy cleanup, vs. no (oil-based) sealer to hand. When I used the original material for shelving in the house I put on multiple coats of white enamel to make it look good, but up there any old stuff will do. It's not a visual thing but more that it could be up there for 10-20 years and will rarely if ever get looked at, so if it's slowly turning to wood-pulp mush due to moisture absorption...

mdf

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#3261931 20-Jul-2024 22:19

timmmay:

If something goes wrong you can always buy another piece of wood relatively cheaply. You don't have a lot to lose giving it a go I'd have thought.

Any thoughts @mdf?

😂 Three coats of a nice oil lacquer and I'll be as happy as a pig in muck.

MDF will be fine unpainted in an attic IMHO. That said, if your dead set on painting it, rolling a couple of coats of APU and a top coat or two while it's on the ground will take next to no time.

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Gordy7

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#3261936 20-Jul-2024 22:31

For non-water based quick paint jobs I use el-cheapo paint brushes and throw them away after use rather than wasting and disposing cleaning solvents.

If a second coat is required I wrap the brush in plastic film so that the bristles don't harden.

Gordy

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mdf

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#3261937 20-Jul-2024 22:34

These are genius: https://monarchpainting.co.nz/products/mini-rollers/

My undercoat roller has been in its container in the fridge (unwashed) for at least a year.

Ge0rge

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#3261938 20-Jul-2024 22:41

I'm curious about the electronics now 🤔

SepticSceptic

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#3261940 20-Jul-2024 22:56

MDF will eventually sag with anything more heavier than a box of tissues.

If you can, slice of a 5cm wide strip.
Join - glue n screw, the edge of the cut strip unneath the shelf.
Like an "L".

MarkM536

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#3261941 20-Jul-2024 23:18

MDF works alright in a roof space.

As said, it does sag if there is no frame for support. Even with a frame is sags in the middle were it's unsupported.

Temp & humidity min/med/max graph from a temp sensor in the roof and Home Assistant logging it. 8-Oct-2023 till 19-Jul-24 in this image. Max temp reached 52c, lowest -1.2c.

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neb

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#3261945 20-Jul-2024 23:49

Ge0rge: I'm curious about the electronics now 🤔

Modbus-TCP to Modbus-RTU gateway to control the HVAC system that's up there, meaning I can control it directly from HA. I'll also put Modbus temp/humidity sensors up there while I'm at it for HA to check, that bit seems fairly close to what @MarkM536's reported using.

In terms of varnish use, I use foam brushes off Aliexpress, you don't have to worry about brush strokes when using them and you buy them in packs of 20 or 50 or whatever so they're more or less disposable.

neb

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#3261946 21-Jul-2024 00:01

SepticSceptic: MDF will eventually sag with anything more heavier than a box of tissues.

If you can, slice of a 5cm wide strip.
Join - glue n screw, the edge of the cut strip unneath the shelf.
Like an "L".

Yeah, did that with the shelving I'd originally got it for, so supported back and sides and with pine nosing at the front. In this case the Sagulator is saying I'm OK, it's 18mm MDF with about a 60cm span and 30cm deep, but I'll see if I've got some scrap pine I can stick on the bottom.

Handle9

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#3262100 21-Jul-2024 12:01

neb:
Ge0rge: I'm curious about the electronics now 🤔

Modbus-TCP to Modbus-RTU gateway to control the HVAC system that's up there, meaning I can control it directly from HA. I'll also put Modbus temp/humidity sensors up there while I'm at it for HA to check, that bit seems fairly close to what @MarkM536's reported using.

In terms of varnish use, I use foam brushes off Aliexpress, you don't have to worry about brush strokes when using them and you buy them in packs of 20 or 50 or whatever so they're more or less disposable.

Why not just attach it to the plant with DIN rail? That’s how they are commonly installed although you’d normally run RTU back to the MCP so you don’t need to deal with getting power up there.

antoniosk

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#3262103 21-Jul-2024 12:08

When we first moved in to our house in wellington, I got a whole swag of shelves from mitre 10 (when they were in tory st) to place on the roof rafters and form a solid base so we could store stuff up there. unpainted and unsealed (300x1800x10mm for $10 each), and have been in the roof space for nearly 15 years, have survived rain and a roof replacement.

I don't know where you live, but they will sag over time and use (these have moved a small amount over that time from the weight of stuff) as others have said.

Really its up to your personal flair and what things will look like up there but unpainted should be fine.

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