Problem Solving Forum (128)


Is there any problem measuring the DFT of an MIO coating ussing an electromagnetic induction gauge?


What are the reasons for different dew points from a sling psychrometer and a digital dew point meter at the same site, and what should be done?


How do you determine whether a lead-bearing coating can be overcoated or removed and replaced?


We are restricted to applying road marking paints during hot, humid summer nights, on surfaces very often below dew point conditions. What is the best generic type of marking paint to use?


What is the difference between the coalescence mechanism and the solvent evaporation mechanism regarding the paint film formation?


How do you gauge the remaining service life of a weathered alkyd paint system and determine whether it should be removed or overcoated?


How does the concave or convex curvature of a surface affect the WFT reading?


During newbuilding, do I have to stripe coat edges if I am using an edge retention primer?


When the relative humidity in a paint shop exceeds 80%, how can you apply waterborne inorganic zinc so that it cures sufficiently for topcoating in a reasonable time?


When performing maintenance painting of tank coatings, what are the pros and cons of overcoating an existing lining that appears to be in good condition?


How do you measure the DFT or WFT of a film-forming sealer applied to a metallized coating (e.g., flame-sprayed zinc)?


How many times can a building be repainted before the paint becomes too thick to perform properly?


Is it necessary to holiday test the interior lining in the vapor phase (roof) of water storage tanks after coating?


How do you successfully apply a chemical-resistant lining to the interior of small-diameter pipes (3 inches or less)?


What are the most effective procedures for protecting steel and adjacent concrete together?


What are the options for shop-applied systems (surface preparation and coating type) to protect the interiors and exteriors of new saltwater storage tanks and associated steelwork that will be exposed to seawater, and that will allow for easy touchup and maintenance once the structures are erected?


How do you adequately assess the adhesion of a newly applied coating?


I need to embed a metallized culvert liner on concrete. I've been told I have to paint it to avoid adhesion problems between the metal liner and the concrete. Is this true and, if so, what type of coating is best?


How can you determine if a concrete substrate is in suitable condition for application of an acid stain?


What is best way to remedy over-thickness of a topcoat after it has dried and cured?


How is it possible to determine if concrete is sound enough to receive a thick-film coating?


How do you measure wet film thickness on shop-applied organic zinc-rich primers to accurately predict dry film thickness?


What components of an onshore shale gas drilling rig require coating protection, and what properties must the coatings have?


In reviewing the testing data for adhesion, some manufacturers indicate ASTM D4541 results while others show ASTM C3359 results. Is it possible to compare one against the other? For example, does 1037 psi provide better adhesion than 4A?


How can you determine the moisture content of a concrete block (CMU) wall, and how can you judge when the moisture level is sufficiently low to paint?


What are the significant differences in performance between an inorganic zinc primer (ethyl silicate) and an organic zinc primer (epoxy), given the same application and exposure conditions?


ASTM A780 says zinc-rich paints for repairing hot-dip galvanized damage must contain either between 65-69% metallic zinc by weight or greater than 92% metallic zinc by weight in dry film. Why is only 65-69% or above 92% accepted? Is any zinc-rich paint out of these ranges not suitable for HDG repair?


If I apply 140 microns of inorganic zinc to a steel substrate with a 75 micron profile, is there any concern about cracking of the primer during storage, shipment, and erection of the structure, or with field-application of a topcoat?


How do you determine the size of the dehumidification equipment required for a tank lining project?


Does roller nap decrease the lifespan of a three-coat OZEU (organic zinc prime coat, an epoxy intermediate coat and a urethane finish coat) paint system? Is there a visual guide or specification for this in the industry or test results available for study?


During a week of heavy rain, we painted the interior walls of a heated concrete building. On the interior of walls that had an outside exposure, the paint blistered badly a week after the rain subsided. Could the rain have caused the blistering and, if so, how?


What surface treatment is best when the maximum manufacturer recommended interval for overcoating has been exceeded?


Where are errors most likely to occur when measuring dry film thickness on steel, and how can they be avoided?


Is the MEK rub test a conclusive test to check the cure of IOZ coatings?


Why would a pull-off adhesion test give a high value (no failure) for a solventless epoxy that later showed poor adhesion in service?


How does concave or convex curvature of a surface affect the WFT reading?


What health and safety precautions should contractors take when applying isocyanate-cured epoxies in the field?


What is the best method for removing production machine oils soaked deeply into a concrete floor before applying a non-skid coating?


What factors would justify coating stainless steel in water or wastewater service? What standards and methods apply?


When applying a 100% solids, fast-curing polyurea coating on concrete, what is the best method for verifying that the proper thickness has been applied?


Specifications often state that glossy surfaces must be dulled before overcoating. What are some methods for doing this, especially when sanding isn’t feasible or desirable?


What steps must be taken to mitigate poor adhesion over an existing aged silver aluminum paint? What primer will achieve good adhesion?


How does the concave or convex curvature of a surface affect the dry film thickness reading?


What is the effect of the wind-chill factor on the curing of epoxy and PU when temperatures are similar?


I have several water tanks constructed with carbon steel for demineralized water storage. The tanks are about 20 years old, and the original coating has started to blister. For refurbishment of the coating, what material should be used and at what dry film thickness? The original type of coating is unknown.


What is the maximum number of holidays that should be permitted for linings used in immersion service, and why?


What is the Cold Wall Effect? Can it cause premature coating failure and, if so, how do I prevent or minimize it?


How much detail should be included in a specification for the surface preparation and painting of a parking garage exterior that includes tilt-up and structural concrete substrates?


How should a contractor respond when he reads a specification requirement that "the nominal dry film thickness of the coating shall be 3 mils"?


What are some ways to improve transfer efficiency of airless spray application?


How do you properly coat welded joints?


Is it sufficient to specify simply that paint should be applied "according to the manufacturer’s instructions?" If not, what kind of detail should be included?


Can water be sprayed onto an IOZ coated surface, which has not fully cured due to low humid conditions, to accelerate the cure?


How do I determine when a cementitious-based mortar used to repair exterior concrete is ready to be coated?


Under what conditions should stainless steel be painted in the oil and gas industry?


Should 304 stainless steel pipework be coated prior to insulation?


What is the difference between a damp-surface tolerant and a wet-surface tolerant paint? How can we determine when a surface is damp or wet?


During a week of heavy rain, we painted the interior of a heated concrete building. The paint blistered badly a week later on the walls with an outside exposure. What’s the best way to remove the coating, prepare the surface, and recoat to prevent future blistering?


How do I prepare an oil-stained, bare concrete floor for coating?


How do you prepare flame-cut edges for application of thermal spray metallic coatings? The problem is that these edges are often harder than the abrasive, so a very low profile is produced, resulting in lower-than-specified adhesion of the thermal spray to the steel.


When is it cost-effective to use thermal spray in petrochemical facilities?


Are there special primers and surface preparation requirements for painting unpainted aluminum?


If a zinc rich epoxy primer has been applied at lower than the specified thickness, how should this be treated?


What are the best solutions (and limitations) for refurbishing small diameter (less than 10-inch) embedded pipelines with multiple bends?


When performing maintenance painting of tank coatings, what are the pros and cons of overcoating an existing lining that appears to be in good condition?


What components of an onshore shale gas drilling rig require coating protection, and what properties must the coatings have?


How do you repair polyurea coatings?


When refurbishing an old concrete secondary containment wall around a storage tank, what criteria should be used to determine if a crack can be repaired for coating or if the section of the wall should be rebuilt?


How do you overcoat an aged inorganic zinc coating?


When applying a 100% solids, fast-curing polyurea coating on concrete, what is the best method for verifying that the proper thickness has been applied?


What is the best way to remedy over-thickness of a topcoat after it has dried and cured?


What factors would justify coating stainless steel in water or wastewater service? What standards and methods apply?


Under what conditions should stainless steel be painted in the oil and gas industry?


How do you repair delaminated areas of an elastomeric polyurea when the majority of the coating system is intact?


How does one apply thin polymer coatings to installed tubes or pipes with diameters of one to three inches and lengths of 20 to 60 feet?


Can fluoropolymer coatings that are still very glossy be overcoated (if, for example, the topcoat is losing color or the color needs to be changed)? If so, what type of coating can be used, and what surface preparation is required?


When we use field splice plate connections on structural steel projects, how do we prevent rust and rust staining at bolt heads and at the splice plate/steel interface?


What are some ways to improve transfer efficiency of airless spray application?


How can I determine when concrete has cured sufficiently to be coated, besides waiting the 28 days typically specified?


What is the effect of the wind-chill factor on the curing of epoxy and PU when temperatures are similar?


Does roller nap decrease the lifespan of a three-coat OZEU (organic zinc prime coat, an epoxy intermediate coat, and a urethane finish coat) paint system? Is there a visual guide or specification for this in the industry or test results available for study?


What surface treatment is best when the maximum manufacturer recommended interval for overcoating has been exceeded?


Should you paint the stainless steel outfitting (ladders, supports, etc.) in steel cargo tanks of chemical tankers?


What are the criteria for selecting coatings for application during extreme (atmospheric) heat?


What coating problems are likely in storage tanks that have dissimilar metal sides and floors?


We are restricted to applying road-marking paints during hot, humid summer nights, on surfaces very often below dew point conditions. What is the best generic type of marking paint to use?


If the walls of single-wythe CMU with core fill insulation become saturated, can they be adequately dried out for painting? If so, how?


How many times can a building be repainted before the paint becomes too thick to perform properly?


How many times can a building be repainted before the paint becomes too thick to perform properly?


What is the best method for preparing newly galvanized steel to be overcoated with an epoxy system?


What can be done to prevent rust bleed in crevices when applying a zinc/epoxy/urethane system?


What are the criteria for selecting coatings for application during extreme (atmospheric) heat?


Under what conditions should stainless steel be painted in the oil and gas industry?


What is the best way to ensure successful application of an acid stain to an existing horizontal concrete surface?


Where can I find industry standards for air quality during spray painting operations, specifically regarding moisture, oil and particulates?


Is it sufficient to specify simply that paint should be applied "according to the manufacturer’s instructions?" If not, what detail should be included?


How should a contractor respond to a specification requirement that “the nominal dry film thickness of the coating shall be 3 mils?”


How does one apply thin polymer coatings to installed tubes or pipes with diameters of one to three inches and lengths of 20 to 60 feet?


Can fluoropolymer coatings that are still very glossy be overcoated (if, for example, the topcoat is losing color or the color needs to be changed)? If so, what type of coating can be used, and what surface preparation is required?


How do you prepare flame-cut edges for application of thermal spray metallic coatings? The problem is that these edges are often harder than the abrasive, so a very low profile is produced, resulting in lower-than-specified adhesion of the thermal spray to the steel.


Can fluoropolymer coatings that are still very glossy be overcoated (if, for example, the topcoat is losing color or the color needs to be changed)? If so, what type of coating can be used, and what surface preparation is required?


What are some ways to improve transfer efficiency of airless spray application?


How can I determine when concrete has cured sufficiently to be coated, besides waiting the 28 days typically specified?


What is the effect of the wind-chill factor on the curing of epoxy and PU when temperatures are similar?


How do you properly coat welded joints?


Can water be sprayed onto an IOZ coated surface, which has not fully cured due to low humid conditions, to accelerate the cure?


During newbuilding, do I have to stripe coat edges if I am using an edge retention primer?


Is the MEK rub test a conclusive test to check the cure of IOZ coatings?


What differences in performance and speed do you see among plural-component, conventional airless, and conventional air spraying equipment for field painting structural steel?


How many times can a building be repainted before the paint becomes too thick to perform properly?


How long after blasting can stainless steel be left before painting? If this time is exceeded, what further surface preparation is required?


If a paint data sheet notes a required primer thickness of 125 microns, but the project specification calls for 50 microns, how is this resolved?


How do you adequately assess the adhesion of a newly applied coating?


When the relative humidity in a paint shop exceeds 80%, how can you apply waterborne inorganic zinc so that it cures sufficiently for topcoating in a reasonable time?


When performing maintenance painting of tank coatings, what are the pros and cons of overcoating an existing lining that appears to be in good condition?


What is the best method for preparing newly galvanized steel to be overcoated with an epoxy system?


When applying a 100% solids, fast-curing polyurea coating on concrete, what is the best method for verifying that the proper thickness has been applied?


Are there special primers and surface preparation requirements for painting unpainted aluminum?


Specifications often state that glossy surfaces must be dulled before overcoating. What are some methods for doing this, especially when sanding isn’t feasible or desirable?


How do you successfully apply a chemical-resistant lining to the interior of small-diameter pipes (3 inches or less)?


Lighthouse Painting: I'm with a Massachusetts municipal park department and have been ordered by the city's administration to "get the lighthouse painted." I know there's far more to it than just grabbing a brush and a can of paint. I need to know how to write specifications for a bid for such a project, as well as how to locate companies that might want the job. Since I'm starting from scratch here, any information or references would be greatly appreciated.

Submitted by reader William Woolley


What steps must be taken to mitigate poor adhesion over an existing aged silver aluminum paint? What primer will achieve good adhesion?


What is best way to remedy over-thickness of a topcoat after it has dried and cured?


Under what conditions should stainless steel be painted in the oil and gas industry?


What is the effect on the permeability of a coating when you add additional coats, either at the time of the original painting or as a maintenance activity?


How do you measure wet film thickness on shop-applied organic zinc-rich primers to accurately predict dry film thickness?

Our shop applies a great deal of OZ primer, and we have found that WFT readings with a standard gauge are not accurate predictors of DFT.


How does residue from chemical stripping affect the performance of the replacement coating?


Is it sufficient to specify simply that paint should be applied "according to the manufacturer’s instructions?" If not, what kind of detail should be included?


 
 
   

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