Page 1 of 3 123 LastLast
Results 1 to 10 of 24

Thread: NHMC and Duct Seal Heat-Resistance Trial - Experimental Design Help

  1. #1
    Founding Member
    Join Date
    Aug 2010
    Posts
    274

    NHMC and Duct Seal Heat-Resistance Trial - Experimental Design Help

    This thread is a follow-up based on this post.

    I found my extra NHMC from Hobby Lobby (the 5lb bricks), and I've purchased two brands of duct seal.

    1) Gardner Bender 1 Pound, 10Pack Plugs Duct Seal Compound - DS-110 at The Home Depot
    2) Ideal.

    Here's what I was thinking of doing: take maybe
    1) 8 1oz (have a postal scale) samples of each
    2) arrange them in random squares on a cookie dough sheet covered in aluminum foil (randomized block design)
    3) bake them at 250deg F for three hours
    4) Drain any oils.
    5) Weigh them
    6) Chart the delta-mass for each block
    7) Run an anova to see if there's any statistical difference between the three groups

    Any thoughts on how I could tighten things up, maybe? I haven't done anything "science-y" in a few years, so any help from smarter people would be appreciated.

  2. #2
    gyroscopes and infrared FoxForce's Avatar
    Join Date
    Aug 2010
    Posts
    155
    Why 250* F? Seems too hot for "real life" carry over to me.

    Here's the MSDS on the stuff I've been using: http://www.engproducts.com/pdf/MSDS/...l_Compound.pdf

    EPCO puts temp tolerance at -40 to 180* F. Not sure what may become volatile/hazardous in the ingredients going above spec. Suppose you could look each up.

    Also, which NHMC brand will you be using?

  3. #3
    Tester Extraordinaire ErinH's Avatar
    Join Date
    Aug 2010
    Posts
    1,247
    My first question is what is your goal with this experiment?

  4. #4
    gyroscopes and infrared FoxForce's Avatar
    Join Date
    Aug 2010
    Posts
    155
    Quote Originally Posted by ErinH View Post
    My first question is what is your goal with this experiment?
    Just a random guess, but heat tolerance?? :p

    If you could get some solid data on "stickability" that would be great. I'll give you anecdotal evidence that DSC it will stick and stay on outer door skins for at least a year through -20 to 100* F (ambient air temps).

  5. #5
    Devil's Advocate Adam_MSS's Avatar
    Join Date
    Aug 2010
    Posts
    1,578
    Real Name
    Adam
    Most critical thing would be having a balance sensitive enough to measure the mass to sufficient sig figs to allow more robust statistical analysis as I'm guessing losses over three hours to outgassing and melting are going to be modest relative to original weight. Aside from that, increasing sample size always helps, 8 should be pretty good.

    I'd stagger the blocks rather than randomizing them. So if you have 3 products and 8 samples of each, I'd look at doing:

    123123
    231231
    312312
    123123

    That should minimize any variation due to temperature gradients across the oven. Each type has 5 samples at edges, 3 on the interior, 2 in the front row, 2 in the back row.

    I'm inclined to tell you to have each piece on it's own piece of foil. You'd have to make sure to get the tare weight of the foil alone, then the weight of the sample+foil before, and then sample + foil after. That might be a bit over the top though, and again, you'd need a sensitive balance.

    What's the resolution on your scale? Something like Parts Express part number 390-768 might work (PE banner up top). I actually received one with a woofer tester today (currently running a special for the WT3 + balance for $99) but the batteries were DOA, so I haven't tested it yet.
    You don't use science to show that you're right, you use science to become right. - R.Munroe

    The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. - W.L.Bragg



  6. #6
    Founding Member
    Join Date
    Aug 2010
    Posts
    274
    Quote Originally Posted by FoxForce View Post
    Also, which NHMC brand will you be using?
    Deprecated Browser Error

    Quote Originally Posted by ErinH View Post
    My first question is what is your goal with this experiment?
    Simple answer: see if either of the duct seal products will not make an oily mess on my doors. The NHMC did.]

    Quote Originally Posted by Adam View Post
    Most critical thing would be having a balance sensitive enough to measure the mass to sufficient sig figs to allow more robust statistical analysis as I'm guessing losses over three hours to outgassing and melting are going to be modest relative to original weight. Aside from that, increasing sample size always helps, 8 should be pretty good.
    That's a good point. Turns out my postal scale has a resolution a sig-fig less than I thought. 0.1oz resolution. So I should probably make the individual samples.

    I like the staggering, and the individual foils as well. Actually, they make cupcake forms out of foil, I think. That might be easier, because I'm lazy.

    (Though in truth that's for MSS. For me, the one that consistently doesn't leave a puddle of oil in the foil is the one I'm going to redo my doors with.)

  7. #7
    Moderator
    Join Date
    Aug 2010
    Location
    Maryland, US
    Posts
    32
    I'd first want to have an idea of what is going to happen - bake the 3 samples, just to see what happens. There could be unexpected results that will ruin your carefully planned experiment.

    Rather than testing many samples of each product at each time, I'd do 1 sample of each and repeat the test several times. I'd also want to put them on a vertical surface since that how they will be used. Put identical oven thermometers on either side of the experiment.

    I'd do 3 rounds at 180F to see if there are problems with short term exposure at temps that can be achieved in a car door. Then I'd do 3 rounds at 250F to try and simulate long term durability.

    Be prepared for the samples to fall off or melt. You want to catch the mess somehow instead of letting it fall into the oven.

  8. #8
    Founding Member IBcivic's Avatar
    Join Date
    Sep 2010
    Location
    MTL, Qc
    Posts
    143
    Real Name
    Martin
    I've tested Thomas & Betts brand, duct seal putty, @ 200 deg. F for over an hour' on a vertical surface and there was no sag or leaching whatsoever. I have also ,just recently purchased G & B brand , from H-depot and that will get torture tested this week-end. I also had a look at the Ideal brand @ Lowes and it seemed to come from the same manufacturer, identical packaging,ect... Only the sticker/label indicated the brand. There was a substantial price difference between the two, but that could of been a local thing, since i was in Alaska at the time. [pricing is a little higher over there]
    I will report my findings and take a few snapshots of the test rig.

    btw , nice to see some familiar faces on here

    Martin
    Last edited by IBcivic; 09-19-2010 at 04:00 PM.

  9. #9
    Founding Member IBcivic's Avatar
    Join Date
    Sep 2010
    Location
    MTL, Qc
    Posts
    143
    Real Name
    Martin
    With my wife, out of town, I am using the oven to quickly evaluate the heat resistance of duct seal putty.
    The T&B brand is a proven product, since i have been using it in my ride for about a year, now and it hasn't sagged or leached oils and has remained as pliable since the day i put it on.
    The G&B [home-depot] duct seal seams to have nearly identical properties [hardness, pliability] but does not have the T&B's incredible adhesive properties, but I'd say...it is 90% there. I'd say that the product is still very much worthy of consideration since it is about half the price of the Thomas & Betts putty.
    Last edited by IBcivic; 09-19-2010 at 05:49 PM.

  10. #10
    Founding Member IBcivic's Avatar
    Join Date
    Sep 2010
    Location
    MTL, Qc
    Posts
    143
    Real Name
    Martin
    Stuck to the sides of an empty coffee can, that provides the vertical surface, I have clearly labeled the 2 samples to be torture tested.

    Here are the pics before entering the oven
    Attached Images Attached Images   

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •