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Topic: Leak revisited (Read 2022 times) previous topic - next topic

Re: Leak revisited

Reply #20 –
FWIW, I was an avid boater, and this is what I was told. 
Silicone is good but not as long lasting as is polyurethane.  There is a product called Boat life (or boatlife) that is excellent for sealing leaks for boats (and FT).  A general rule is that if you want to remove something later or feel you would use silicone, very infrequent removal use polyurethane caulk, and  if you think you will not remove then use 3m 5200 caulk.  My belief would be use silicone for the new led clearance lights (if that were the case) and for leaks either 5200 or polyurethane. 
As may be apparent, the less likely to remove the more tight the bond, and harder and hardest to remove the caulking.  Thus polyurethane would be good in a leak, as we don't want it coming off anytime soon. 

Re: Leak revisited

Reply #21 –
Steve,

When you replace the screws use stainless steel, but also a high grade. Many that you find at Lowe's, Grainger, Menards, and Home Depot are good, but they tend to be soft. Try to get screws near 304 grade. There are different grades of stainless steel too (approx. 150 grades). Pay extra and never revisit the problem again. Do it right or get out of the fight, my father always told me about the work we do. Hope this helps too. Mr. Scruggs thanks for the info. I will mark that one down. I am into glues that last until I am 200. ^.^d

Curtis

Re: Leak revisited

Reply #22 –
Well first I am not a tech on caulks but have learnt over many years doing bath and kitchen reno's that Silicone is good for the short time but it can come seperated from the 2 componants it is trying to hold together and you will not know it till it is too late. It is virtually impossible to get silicone caulk to stay bonded for a long time, and remember all the extremes of weather etc we put our coaches thru'. Polyurethanes stay slightly soft and seem to want to re-attach itself for a long time, is great for high temps and low. 3M 54 is a good one as is Locktite.
John H

Re: Leak revisited

Reply #23 –
Generally, I rate the quality of stainless by a simple method, if it sticks to a magnet= low quality, if not= better quality.  I did use silicone and feel it will work because I injected in to the screw holes, then put the original screw back in. Not much chance for the silicone to fail.  I was out of polyurethane sealant, or would have used that, it is much better stuff. I will do all the rest of the exterior screws that penetrate the shell today.......
Steve

Re: Leak revisited

Reply #24 –
Quote from: Gayland Baasch –
John - inquiring minds want to know, why not silicone?

Gayland, urethane has much better adhesion to most surfaces and is therefore a better choice for waterproofing. Urethane caulk is basically is a combination of caulk and adhesive. Just make sure that the surfaces being caulked are clean and oil free and it will last for years. Quality urethane, when compared to silicone, is typically more UV resistant, has better tensile strength and better elongation. As an example, all of the old white urethane caulk used on the original build of my 93 coach is still in great shape. Urethane is also harder to find but Dicor and Sika urethane caulk seem to be readily available at camping supply stores and home/hardware stores. 

There are basically two kinds of urethane caulk: high modulus, non-sag caulk for vertical application and low modulus or self leveling for horizontal application. If you can only get one, get the high mod. It can be used either way. 

I do not recommend Acrylic or Acrylic-Silicone under any circumstances.

Just the ramblings of an of Goo Guy!!!
 

Re: Leak revisited

Reply #25 –
Kent, is urethane the same as polyurethane?