How to fix warped front trunk liner cardboard

[ard]

I did a search and the results pertained mostly to dashboards and rear parcel shelves, which is not exactly what I am looking to do. However, if this has been discussed feel free to redirect me.

The heavy cardboard insert which sits in a pocket on the flat part of the frunk liner where it covers the spare tire in my 993 has become quite warped (see pics).

Has anyone successfully straightened out the liner? The interwebs suggest flattening cardboard by immersing it in water, and weighting it down by something flat and heavy. I worry that might swell the fibers excessively and destroy the liner, which is made of quite sturdy cardboard. I am thinking about making it pliable by using a steam clothes iron set at a very low temperature setting and then clamping it between 2 pieces of plywood.

I'd welcome any other ideas.

TIA,

/alex

[Coastr]

Your method sound good though a kettle might work better to give a continual flow of steam. You want to get it warm and pliable without soaking it wet.

[smadsen]

That looks to be a generic hardboard product, or it used to be referred to as "Masonite." The stuff, or something similar, is pretty cheap at the lumber store. Usually comes 4' x 8' sheets like plywood, but some places sell 2' x 4'. Can you use the bent one as a template and cut a new one?

[Quickstep192]

I would say the keyword is “dampening” more so than “soaking”.

Once completely dry, saturating them in epoxy will help them retain their shape. Just keep brushing the epoxy on until it won’t absorb any more. Use slow curing epoxy so it has more time to soak in.

[ard]

Originally Posted by smadsen

That looks to be a generic hardboard product, or it used to be referred to as "Masonite." The stuff, or something similar, is pretty cheap at the lumber store. Usually comes 4' x 8' sheets like plywood, but some places sell 2' x 4'. Can you use the bent one as a template and cut a new one?

I thought about that - it's an essentially invisible part (tucked into a pocket in the frunk liner) but I don't know the following:

1. how to cut the Masonite cleanly - it looks too sturdy for a utility knife and a hacksaw would leave an untidy edge
2. whether the edges will fray over time - when I look at the factory piece it looks like the edges have some light sealant applied

I may see whether I can source a suitably sized piece of Masonite to have as a backup while I play with straightening the original piece.

[smadsen]

Originally Posted by ard

I thought about that - it's an essentially invisible part (tucked into a pocket in the frunk liner) but I don't know the following:

1. how to cut the Masonite cleanly - it looks too sturdy for a utility knife and a hacksaw would leave an untidy edge
2. whether the edges will fray over time - when I look at the factory piece it looks like the edges have some light sealant applied

I may see whether I can source a suitably sized piece of Masonite to have as a backup while I play with straightening the original piece.

I would cut Masonite or hardboard with a jigsaw and the finest blade you can find. The true Masonite product is pretty dense and should cut cleanly.

Good luck however you go.

[Coastr]

Still think it’s worth steaming the original part. It will be less work than cutting out a new one

[Showdown]

I deal with Masonite and hardboard at work a lot along with other fiber materials and flattening them is often a request (painting conservation) and I’ll save you the hassle: don’t bother.

I have heat tables, vacuum tables, presses and all sorts of devices and no matter what, the bow or warp will return in some capacity.

Just replace the warped piece. A sheet of Masonite or other hardboard is cheap and cuts like wood: a fine blade and a bit of sandpaper and you’re fine. The edges won’t disintegrate for 30 or so years but if you’re concerned, just paint them with some thin epoxy (no water based adhesives as water will destroy hardboard)

[AG81]

Showdown 's advice is excellent. I deal with Masonite, OSB and Particleboard regularly.
All are junk after exposure to moisture and/or water. Shape retention is futile.
Start over with something new or use aluminum. Rennline piece shown.

[eastbay]

Part of owning an older Porsche is being able to work with wood and fiberboard. Unlike an American car. lol.

I have reshaped or flattened glove boxes, door cards and pockets, rear parcel shelfs and trunk dividers.

The secret is to soak the pieces until they are wet enough to be pliable (usually all the way through). Then thoroughly clamp or weight the pieces to the desired shape. Will take several days to a week to dry. Don't release weights or clamps until 100% dry or they will memory warp again.

On your piece I would soak until pliable and then place on smooth concrete and weight with a piece of thick plywood or melamine or any other thick rigid board that is larger than the piece itself. The finish retained on your piece will reflect the smoothness of your weight board and concrete. Probably will need 25lbs or more for weight, something like a couple of concrete blocks.

[EC900]

This Old House would always advocate for more clamps, you can never have too many clamps.
You’re on the right track, it’s a slow process. Drying too quick it warps, drying too slow could lead to mold. If you have access to a carpet steamer rental, that would be faster than an iron, some furniture reupholsters might have equipment too. When shaping drywall or wood veneer on a curved stair riser trim, depends on thickness, it’s done over time using many clamps, inch by inch. Using round shapes like pvc pipe or buckets help achieve a curve slowly when clamped in small sections. When it comes time to paint, mdf or fiberboard needs a shellac oil based primer coat, like B-I-N, Zisser - don’t use a water based primer it will not will absorb and ruin the fiberboard and will cause a topcoat to fail.
I’m not familiar with 993 but early 911 had two brackets that have the fiberboard cover was pop riveted into the curved contour. If you have these brackets, attach a pliable section one at a time over the course of days. Replacing would be easier if there are these mounting brackets.
That said have you considered Kydex? Bends, contours and is permanent x after warming it to 200° in an oven, but a bit expensive.
Or how about HDPE sheets found at Menards in various thicknesses.
The size on a 911 is 9 x 28.

[mikokalin]

I found this topic and I was wondering if you succeeded. If the problem is still not solved, there is a trunk mat with a rigid insert.

[ard]

no that project is still on my to-do list. Some good suggestions in this thread. When I tackle this (maybe hopefully over 4th of July) I'll post the results here.

Cheers