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Open Cell Shrinkage Post New Topic | Post Reply
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Tom Bacon
Posted: Jan 18, 2012 11:27 AM
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Open Cell Shrinkage
Hello Mason and all other applicators, I am currently having an issue with shrinkage and need advice.Product is Demilec Selection 500, temps are 130 A,125 B, Line 120, Air is 1250. Problem is once sprayed the material literally shrinks, losing a inch to a inch and a half of expansion. Substrate is plywood. Any ideas on the shrinkage issue?
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jimcoler
I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Jan 18, 2012 11:41 AM
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It sounds like it's a blockage in the gun. Over 95% of the time it's a gun issue with it not mixing properly. |
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Tom Bacon
Posted: Jan 18, 2012 11:44 AM
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As far as the foam cells they are almost perfect, that is why i ruled out it being mechanical, as far as the gun is concerned. |
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Tom Bacon
Posted: Jan 18, 2012 11:58 AM
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Spray pattern is near perfect, spraying with a 2929. started off with no issues and dropped the temps due to the time of day, 78 at that current time I beleive. |
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mason
Posted: Jan 18, 2012 02:40 PM
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Contact Demilec and talk to their technical rep. Provide him with all details of the work, climate, substrate temperatures, moisture content, humidity, pressure\temperature of the euipment, type of proportioner, spraygun, and spraygun configuration (mixing module, chamber, pcd, etc.) Things that cause foam to shrink poor mix, cold substrate moisture on substrate B side not agitated moisture in your b side from condensation moisture in you airline from condensation in your drum old material cold material. off spec foam Demilec's tech rep should be able to take your specific job conditions and help fix the problem. If not, try a few of the equipment distributors out there such as Intech or Sprayfoam Distributors of New England. Good luck, let us know how it comes out. |
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Tom Bacon
Posted: Jan 18, 2012 03:12 PM
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Thank you Mason, Demilec is sending two reps in the morning, they have been great at handling any issues we have had. One thing I didnt consider was condensation in the barrel. We have a drier for the lines also, so maybe need to check it out also. Tom |
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steven argus
Posted: Jan 19, 2012 06:45 PM
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Try running your B hotter than your A. In the winter, we start out at 145 degrees on the hose and B heater. Then run the A side 10 - 15 degrees cooler. This helps to balance the viscosity. If the foam is still "setteling" turs the tems down 3 degrees every 20 mins. until it stops. Also, make sure your barrel temp on the B is at least 80 degrees, espesially if you run smaller equipment w/ a smaller delta T rating. |
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Gerry Wagoner
Posted: Feb 05, 2012 09:38 AM
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@1250, the air is probably too high. |
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mark moyer
Posted: Feb 06, 2012 05:07 PM
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..are you stirring your resin???? ...we take a "different look" at spinning water based resins than the manufacture...our foam dosent shrink typically btw..lol...they say spin at start up and shut it down... we spin fast at startup and recirc,,and once temps are up and recirc of stratified fluid in hose set is flushed with well blended/heated resin we turn her down but we continue to spin the resin thruout the spray process...no we do not "froth" the resin..gentle agitation...to keep the blend homogenous,, i believe the manus tell you guys to turn em off cause you aint got the power to run the stirrers,,air hogs and elect hogs,,,they like them little bitty gensets,,cheaprigs.com..lol little bitty compressors,, ..just thinkin |
