MTFCA Forum

What kind of sealant would anyone recommend to put on a wooden firewall before painting it?

I used a sprayed on layer of gloss polyurethane spar varnish. I lightly sanded it and then sprayed with black enamel. It came out looking real nice.

This is what I do.

One coat of black primer
after it dries a coat of flat black
apply light coat of black RTV inside of each coil box terminal hole and choke rod holes to prevent moisture from separating plywood layers
let it dry and install

best of luck,
Dom

Sand and wipe with alcohol. Then 1-2 coats of sanding sealer (sand between coats). Then follow Dom's directions.

To preserve the appearance of the grain in the timber, I do not use fillers. The bare timber is coated with a full coat of Penetrol which is a sealer/paint thinner/brushing extender. This soaks right into the grain without hiding it. Then I use a 'wash' of 50% black gloss enamel, 50% mineral turpentine and give it one coat only. It is thin enough to soak right in too, again without filling the grain. this dries to a matt finish just like that on original timberwork.

Allan from down under.

If there is grease or oil on the firewall, I would thoroughly clean it with lacquer thinner until all oil residue is off. After that, I would prime the wood with one coat of Sherwin Williams Oil Based Wood Primer. After it dries (about 4 to 5 days) I would apply a finish coat with 2 coats of Sherwin Williams All Purpose Gloss Black Enamel. Both Primer and finish can be nicely brushed on with a good 2” sash brush. I have posted pictures of the products. In the photo showing the can of black enamel, you can see the spokes I brush painted and how well it looks. Gloss is much easier to keep clean of oil, dirt and grease, than flat or satin finishes. Jim Patrick

Since the skeleton of my speedster body is plywood, I thoroughly soaked it all with Thompson's Water Seal prior to painting. The paint has held well and the wood looks as good as new yet, despite MANY drives through torrential downpours and the occasional stream.

In 1985, when I needed to waterproof the bare wood siding on my house I was building, until I was ready to paint it, I was advised by a Sherwin Williams technician not to use Thompson’s Water Seal for this because, due to its’ silicone base, Thompson’s Water Seal cannot be painted over. I was instead, advised to use “Olympic Water seal” because it is oil based and can be painted over. Before posting this, I went to the Thompson’s Water Seal website and what the Sherwin Williams technician advised 35 years ago was confirmed as still being true. Thompson’s advises not to paint over their water seal because it will not hold. Jim Patrick

jiminbartow wrote: ↑

Sat Nov 21, 2020 9:30 pm

In 1985, when I needed to waterproof the bare wood siding on my house I was building, until I was ready to paint it, I was advised by a Sherwin Williams technician not to use Thompson’s Water Seal for this because, due to its’ silicone base, Thompson’s Water Seal cannot be painted over. I was instead, advised to use “Olympic Water seal” because it is oil based and can be painted over. Before posting this, I went to the Thompson’s Water Seal website and what the Sherwin Williams technician advised 35 years ago was confirmed as still being true. Thompson’s advises not to paint over their water seal because it will not hold. Jim Patrick

Interesting Jim. Maybe my memory is off as to the brand I used. I wouldn't be shocked if that were so. Since my paint has held on really well, I must have not used Thompson's, but some other brand. Thanks!

Jerry- the yellow car? Or do you have another one?

Atomic Amish wrote: ↑

Wed Dec 02, 2020 11:40 am

Jerry- the yellow car? Or do you have another one?

Jason,

Yes! The yellow one. I suppose you see it more than I do these days!

I use high gloss boat varnish for the wood.

Andre
Belgium

40 years of boat building with wood--epoxy techniques has taught me the necessity to thoroughly edge seal laminated wood materials. All other methods pale compared to epoxy encapsulation. Plasticized wood simply cannot absorb water. I have, on hand, gallons of System Three laminating epoxy. Chosen over the West system due to ease of mixing--two to one--resin, hardener, with equal results. Thankful for the sought after door-strap clamp you're sending me, It would please me to send you proportioned elements sufficient to thoroughly stabilize the open grain edges of your firewall. Sand off the resulting raised grain and epoxy smooth shine and the wood is prime for painting. In the case of my '16 firewall, the clear finish reveals no sign of the guardian epoxy beneath. With fast hardener (all I use and have on hand), after warming the firewall edges, with a heat gun, to enhance absorption, you would have about 20 minutes, at around 70 degrees, to liberally slop epoxy until the open grained plies refused it.

With the type of T’s in his profile pictures, I was under the assumption he was after a black finish on his firewalls. Jim Patrick.

jiminbartow wrote: ↑

Thu Dec 03, 2020 12:13 am

With the type of T’s in his profile pictures, I was under the assumption he was after a black finish on his firewalls. Jim Patrick.

You assumed correctly

Jerry VanOoteghem wrote: ↑

Wed Dec 02, 2020 6:16 pm

Atomic Amish wrote: ↑

Wed Dec 02, 2020 11:40 am

Jerry- the yellow car? Or do you have another one?

Jason,

Yes! The yellow one. I suppose you see it more than I do these days!

LOL that's probably true! I'll be spending all of next weekend with it.

Atomic Amish wrote: ↑

Thu Dec 03, 2020 10:33 am

Jerry VanOoteghem wrote: ↑

Wed Dec 02, 2020 6:16 pm

Atomic Amish wrote: ↑

Wed Dec 02, 2020 11:40 am

Jerry- the yellow car? Or do you have another one?

Jason,

Yes! The yellow one. I suppose you see it more than I do these days!

LOL that's probably true! I'll be spending all of next weekend with it.

Tell it Jerry says "hello" please.

Jerry VanOoteghem wrote: ↑

Thu Dec 03, 2020 2:40 pm

Atomic Amish wrote: ↑

Thu Dec 03, 2020 10:33 am

Jerry VanOoteghem wrote: ↑

Wed Dec 02, 2020 6:16 pm

Jason,

Yes! The yellow one. I suppose you see it more than I do these days!

LOL that's probably true! I'll be spending all of next weekend with it.

Tell it Jerry says "hello" please.

Someone says "Hi, Jerry!"

It's looking happy! Thanks!