Heat Resistant Finish

[gMike]

I'm going to be doing some trivets and wondered what is the best finish to resist heat.  I envision people putting a hot pan or dish directly on a wooden trivet.  Normally I would just use wipe-on poly but I have no idea whether it has any heat resistant properties or not?

[jteneyck]

No finish is the best finish on a trivet.  Something like tung oil or Danish Oil would work well if you wipe it completely off.  But any film finish is likely to be damaged by hot casseroles, etc.  If you want to try a film finish, make some samples with scrap and give them a test run with some hot dishes.  

John

[fredhargis]

Best bet would be to have something between the wood and the pot, like a tile or some such.

[wood2woodknot]

I made trivets with 3/4" poplar finished with 3 coats of wiped on Arm-R-Seal. I tested them with 400* pizza pans and heavy china coffee mugs with no ill effects. They have been in use for 2 years and no problems.

If you can find it on the "way back machine" search features, there is a more extensive scientific test of several finishes made by jteneyck. Arm-R-Seal came out best in his tests.

Below is an except I pasted from one of the forum threads back on 4/28/16. Somewhere there is a more extensive separate thread by jteneyck - or contact John here on WoodNet.
________________

jteneyck
(Member)
04/28/16 05:43 PM

Re: Waterbased vs Oilbased polyurethane any durability experience?

I use mostly WB finishes now that I spray in my basement. I did a lot of testing
when I started using them about 5 years ago to see how they compared to OB
polyurethane. Most of my experience is with GF's products. I've posted those
results several times but here's a snapshot:

EnduroVar is as chemically durable as most any oil based varnish, polyurethane
or otherwise. It is harder to spray than HP Poly or Clear Poly, but brushes
beautifully. It has a slight amber tint, but is still lighter than OB varnishes.
Supposedly it ages over time like an OB varnish, but I haven't seen it yet in the 4
years I've been using it. It can get cloudy if you apply too many coats. It's not
KCMA rated but has the highest chemical durability of any WB product I've used
and is on par with ArmRSeal.

Enduro Clear Poly is more abrasion resistant than typical OB varnishes, by far.
Spray only product. It is dead clear and stays that way. KCMA rated. It's my
overall favorite GF product.

GF's High Perf. Poly is very clear and very hard, but not as chemically durable or
heat resistant as the above two products nor typical OB varnishes. However, it
sprays and brushes beautifully. It has a dual UV package that prevents it and the
wood underneath from light aging. It's one of my favorite products except for
kitchen/bath projects.

MinWax Polycrylic is OK, but not in the league of the GF products. It's not
nearly as hard and my limited testing showed it wasn't as chemically durable as
the best GF products so I never use it. However, it sprays great and goes on well
with a foam brush, too.

ArmRSeal oil based polyurethane is my benchmark product for a hand
applied, traditional looking product. Very high chemical and heat durability and
abrasion resistance.

As an aside, GF's oil based Urethane Topcoat has very low chemical durability
and heat resistance. Even water will damage it after a few days.

All of the WB products above dry in less than 1 hour and can be scuff sanded and
recoated in 2 hours. They fully cure in about 7 days. You can finish a project in a
day. Gotta love that.
John

4/29/2016 www.forums.woodnet.net/ubbthreads/printthread.php?Cat=&Board=finishing&main=7274278&type=thread

[Cooler]

I put a mug, hot from having boiling water in it, on the counter top I finished with an oil based (Minwax) poly.  The finish under the mug became cloudy.  After about 4 or 5 days the cloudiness disappeared and there was no permanent damage.  But clearly the finish was not happy with the heat.

The trivets I've made as gifts had a tile on the top.  Here is an example I found on line:

[jteneyck]

Cloudy under the finish was more likely from moisture in the wood than a reaction from the finish.  Had it not gone away after a few days then I think you could conclude the finish was damaged. 

A film finish is more likely to be damaged on top, where the hot pan sits directly against it.

John

[Cooler]

Cloudy under the finish was more likely from moisture in the wood than a reaction from the finish.  Had it not gone away after a few days then I think you could conclude the finish was damaged. 

A film finish is more likely to be damaged on top, where the hot pan sits directly against it.

John

That makes sense.  I still think putting a piece of granite, marble or porcelain tile on the surface is a better choice than relying on a finish to deal with heat.  Especially if it is well above boiling temperature (which can happen if you remove a pan from a stove top).

There are companies that make heat-resistant finishes for exhaust systems on cars.  And this one makes it for wood products (UK).  A standard finish almost certainly will not stand up to extremely high temperatures.

http://www.kortec.co.uk/heat-resistant/

Fire Resistant Coatings For Wood & Metal

Kortec offer heat/fire resistant systems for the protection of both wood and metal. There are typically very critical requirements affecting this type of coating, and we understand the importance of total clarity regarding the specification and protection needed in each situation. There are several categories that fall under this general classification.

[jteneyck]

 I still think putting a piece of granite, marble or porcelain tile on the surface is a better choice than relying on a finish to deal with heat.  Especially if it is well above boiling temperature (which can happen if you remove a pan from a stove top).
s that fall under this general classification.

Agreed.

John