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Discussion Starter · #1 ·
The POR 15 instructions say to apply the product in temps between 50 and 90. My shop was b/n 55 and 60 with the heater on today. However, I don't want to run the heater all night so is it OK to let the temps drop in the shop into the low 20's? ... will it finish drying?

Also, do I need to sand the surface much between coats (I was only able to get one coat on the rearend, spindles and some other misc. parts).

I searched the archives and, although there was a lot of info on POR, none of it had to do with low temps.

TIA,

-Jon A.

[ January 22, 2007, 07:08 AM: Message edited by: Jon A. ]
 

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Jon A,

I'm a coatings saleman. Do not apply if you can't keep the temps b/t 55 and 90 for 24 hrs. It will cause a coatings failure down the road. Always follow the spec. sheet. When the temps drop, the surface temp drops equal to or below dew point. Then the troubles begin. Por-15 is a solvent evaporation cure not a chemical(A/B part)cure. So the atmosphere needs to be correct.

Glenn

Glenn
 

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Discussion Starter · #3 ·
Glenn,

Here are the specs from POR-15. It says that drying is dependent on ambient humidity (it is 36% right now). It doesn't say that temps have to be kept at >50 to dry...


Specs...

Product Characteristics

Appearance: Glossy or semi-gloss (black only) finish.

Application: Brush, roller, spray

Spreadability: 96 sq. ft. per quart, 384 so. Ft. per gallon.

Elongation rate: 79%

Drying Time: Depends on ambient humidity. High humidity equals faster dry time, which varies from 3 to 6 hours.

Porosity: None

Viscosity: 250 - 500cps at approximately 77ºF

Durability: Semi-permanent

Application

1. Using an airless sprayer, brush or roller, apply a first coat to the surface. Appropriate layer thickness: 25-50µm.

2. In order to form a complete anchor, apply the second coat immediately after verifying the dryness condition of the first coat by touch after 1-2 hours have passed. Appropriate layer thickness: 25~50µm.

3. Perform surface treatment with sandpaper after complete hardening and paint a second time.

4. Second coat (50µm) when using external topcoat paint (POR-15 Stirling Silver, Hardnose Paint) takes two hours to dry to the touch but complete hardening takes about four days at 65ºF.

5. For externally exposed areas, paint topcoat with POR-15 Stirling Silver or POR-15 Hardnose (various colors) in order to block from ultraviolet light.

From: http://www.por15.com/s.nl/it.I/id.12/.f?sc=12&category=684&fromsla=T
 

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Por-15 coatings cures by hydrolsis when the reactive resins conbine with moisture from the air to form the hardened (chemically resistant) films. I would be concern with the lowered surface temperature that could cause condensation at the surface. If this is present than bubbles can occur was the water tries to evaporate.

Glenn
 

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POR-15 is a rust-preventive paint designed for application directly on rusted or seasoned metal surfaces. It dries to a rock-hard, non-porous finish that won't chip, crack, or peel, and it prevents rust from re-occurring by protecting metal from further exposure to moisture. POR-15 is sensitive to UV light (sun) and must be topcoated before prolonged exposure to sunlight. POR-15 is cured and strengthened by exposure to moisture and will dry faster under extreme humidity, but moderate to dry atmospheric conditions are most desirable when applying this product, because extreme humidity may cause an immediate surface cure, trapping carbon dioxide gas below the surface. When this happens, bubbling may occur. Extreme humidity at the time of application may also interfere with proper adhesion of the POR-15 coating to metal because it's almost impossible to keep metal dry under such conditions.

glenn
 

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POR-15 APPLICATION PROCEDURES

Surface preparation:
Rusted surfaces are best; seasoned metal and sandblasted surfaces are also good.

To coat smooth metal surfaces:
Use POR-15 METAL-READY to prepare surface before painting. Surface must be dry and free of grease, oil, or other foreign substances. Use of 'rust converter' products is not recommended as they may affect bonding of POR-15 to metal. POR-15 likes to adhere to surfaces with 'tooth' rather than smooth, glossy surfaces.

Glenn
 

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Discussion Starter · #7 ·
Glenn,

Thanks, I followed all of POR 15's application procedures (marine clean, metal-ready then POR 15).

I just went out to the shop and it looks like it is drying. So far there aren't any bubbles. The surface is tacky (and a lot drier than it was a couple of hours ago). The temp is 34 degrees.

Hopefully it dried enough while the heat was still on... I will check it again in the morning.

-Jon
 

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Jon,

Great news! Usually bubbbles occur quickly. Sounds like your surface was dry enough. Good luck with the coatings. I just finished my built but not reg. yet. Sad day for the SAINTS! It may take a little longer to cure in lower temp than a hot day. Colder temp just slow it down. Sould be fine in the morning.

www.garagefreaks.com

Glenn


Glenn
 

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Discussion Starter · #9 ·
UPDATE:

This morning all of the parts are dry and hard (no bubbles). It was 28 degrees in the shop at 6:30.

Thanks for your help Glenn.

PS

Your car and web-site look great (they can't really be viewed in Firefox, only Internet Explorer).

-Jon A.
 

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Discussion Starter · #10 ·
UPDATE 2:

I called POR-15 today and they were very helpful. I thought I would share what they said in case anyone else has questions about using their product in low temperatures.

Essentially, they said that it is best to be able to maintain their recommended temp. range for 24 hours (just like Glenn said). However, since I did not have any problems initially, I have a good bond.

The product dries depending on ambient humidity (it likes humidity but not too much humidity... I am not sure what that translates to in terms of a percentage). (My humidity was 36%).

They also said that the longer I can maintain >50 degrees after applying it the better the chance of the product working.

For my second coat, I am going to scuff with 600 grit, clean and apply... hopefully, I will be able to maintain 50+ for 6-8 hours. I am taking a risk but since it worked once, I am not too worried.

-Jon A.
 
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