Cleaning Techniques

Concrete Floors

Summary

This details the equipment, products and techniques recommended for fast, safe, and effective preparation of concrete floors prior to the application of a floor coating.

Effective water-based cleaning is controlled four key variables:

Time – Length of time the cleaning solution is in contact with the surface
Agitation – Impingement of the cleaning solution on the surface, i.e., scrubbing or the force of high-pressure spray.
Concentration – Strength of the cleaner.
Temperature – The temperature of the cleaning solution. Each +18°F increase in temperature doubles the cleaning rate.

The fastest most effective cleaning method requires the use of a hot water pressure washer that will inject detergent under high pressure. The combined effect of the high-pressure spray, heat and detergency in continuous contact with the soil results in fast cleaning and minimum detergent use.

Increasing any one of the four variables will improve cleaning results. Since cleaning quickly is usually required, increase the temperature, agitation and/or cleaning solution strength to improve cleaning results.

Equipment

• 3,000+ psi hot water pressure washer
• Chemical injection system which allows high pressure detergent injection
• 15° wand tip for routine cleaning
• 0° Oscillating tip for heavy soil removal
• Quick-Disconnect fitting for the wand tip

Detergent

• Great Lakes Laboratories All Purpose Prepaint Degreaser #1921
• USDA Accepted with an A-1 Rating

Preparation

• Adjust temperature to deliver 140°F at the wand tip. Temperatures above 140°F may cause thermal shock to concrete floors in refrigerated work areas.
• Adjust injector for 1 oz. of detergent per gallon of water.

To Determine Injection Rate

1. Fill a measuring cup with water.
2. Place the injector foot into measuring cup.
3. Trigger the wand at high pressure into a 5 gallon pail until the pail is full.
4. Determine how many oz. of water have been drawn from the measuring cup.
5. Divide the oz. drawn from the cup by 5 to determine the oz./gal. injection rate.
6. Adjust the injection control valve to provide the oz. per gallon of detergent required.

Method

1. Position the 15° tip so that the fan spray pattern is horizontal.
2. Work in 10′ x 10′ sections. Begin in a corner and work toward floor drains, if available.
3. Prevent recontaminating treated areas by cleaning boots frequently.
4. Hold wand within 12″ of the floor so that the spray strikes the floor at a 45° angle. This provides the maximum “chiseling” effect and the fastest soil removal.
5. Move the wand at 1′ per second. Push spray to insure complete coverage.
6. Flush floor with hot water after cleaning. For best results, scrub while rinsing using a clean push broom.
7. Use pedestal fans, compressed air or an electric leaf blower to reduce drying time.

Usage Tips

• To determine if the floor is clean, spray water onto a clean, dry area. The water should flow evenly over the surface and wet the concrete. If the water beads or breaks, the surface is still contaminated and should be re-cleaned.
• Heavily soiled areas may require pre-wetting with detergent and scrubbing with a brush or pushbroom or using a 0° oscillating wand tip.

Other Considerations
Some pressure washer manufacturers offer a floor cleaning attachment that can be connected to the hot water pressure washer. Such a unit may further reduce cleaning time and improve cleaning results.
-If floor drains are not available, vacuum up the cleaning solution using a wet-dry vac.

For Technical Assistance Call:

1-800-888-1105

Preparing Galvanized Steel for Painting

Summary
This details a recommended method for prepping sheet galvanized used for ventilation ductwork, roof decking and many other applications. New galvanized steel of this type usually has a clear, glossy, “passivation” film which will cause the loss of coating adhesion if it is not removed.

The passivation film is applied by the galvanizer to prevent the zinc from reacting with water and carbon dioxide during transportation and storage.

Unprotected zinc forms white, powdery deposits of zinc oxides, hydroxides and carbonates, that are commonly referred to as “white rust”, “zinc salts” or “zinc soaps.” If white deposits on an unpassivated zinc surface are not removed prior to coating, coating failure usually occurs.

The glossy passivation film is often misidentified as a wax or an oil. It is neither and cannot be removed by solvents such as xylene. The film is a thin coating of an alkaline liquid, similar to the “cure & seal” used on concrete, which can be removed with Great Lakes Laboratories Clean ‘n Etch, an odorless, acid-based detergent.

Equipment

• Rubber Gloves, Dust Mask
• Safety goggles or face shield
• 2.5 – 3 gallon, all plastic, hand-pump, tank-type, garden sprayer
• Water for rinsing can be applied with an airless sprayer, water hose or garden sprayer.

Procedure

1. Mix 1 part Clean ‘n Etch with 2 parts water.
2. Mix Clean ‘n Etch in required strength using hot water, if available.
3. Adjust the spray nozzle for a medium spray to reduce the aerosol effect.
4. Work in sections to ensure that the surface is rinsed before the solution begins to dry.
5. Wet the surface with the solution and allow 20 minutes of contact time.
6. Rinse the treated section thoroughly with water.
7. Air dry or force dry.

Usage Tips

• Each +18°F increase in the temperature of the solution will double the rate of reaction. Using hot water will reduce treatment time and may reduce the concentration required.
• Use oil-free compressed air or an electric leaf blower to reduce drying time.

Tests for Paint Readiness

• Use the GalvaCheck Passivator Test Kit to ensure that the surface is ready for paint.
• Scan the Qr Code below for an instruction video. 

Troubleshooting
White deposits on the treated surface may occur if the concentration is too strong, the contact time is too long or the solution is not rinsed before drying begins.

These deposits are zinc phosphate resulting from the chemical reaction of Clean ‘n Etch with zinc on the surface and usually do not appear if the surface is rinsed before drying.

A light amount of zinc phosphate will not affect coating adhesion, however, it is good practice to brush off as much of the white powder as possible prior to coating application.

For Technical Assistance Call:
1-800-888-1105

Hand-Wiping Steel

Summary
This recommendation details methods for manually cleaning steel parts, fabrications, subassemblies, machinery, equipment and other components. The methods are suitable for use on new steel as well as on previously painted surfaces.

Equipment

• 2½ gal. plastic, hand-pump, tank-type garden sprayer
  or,
• Airless sprayer with 2 gallon pressure pot
• Measuring cup
• Shop cloths
• Synthetic abrasive pad
• Pedestal fans or oil-free compressed air for dryoff

Method

1. Mix 1 oz. to 10 oz. of Prepaint Cleaner for each gallon of water.
2. Adjust the nozzle to produce a fine spray.
3. Thoroughly wet the part with the solution. Allow 1-3 minutes contact time.
4. Wipe part dry with clean shop cloths, turn cloths frequently for best results. For areas where solution can become trapped, i.e., behind tack welded plates, force dry with oil-free shop air.
5. Once dry, the part is ready for coating application.

Troubleshooting

• Flash rust on hot rolled steel is usually caused by parts remaining wet too long after washing.
• Insufficient cleaning may result from low solution temperature, low solution concentration and/or lack of solution contact with surface.
• Avoid white streaking on clean parts by reducing solution temperature, strength, and/or wash time.

Tips

1. Solution Strength – Use the minimum amount of Prepaint Cleaner required to clean the part.
2. Use Hot Water – If possible, mix cleaner with hot tap water. Each 18ºF increase in cleaning solution temperature doubles the rate of cleaning.
3. Spray, Don’t Dip – Using a sprayer for application insures that the cleaning solution is uncontaminated. Rinsing the cleaning cloth in a pail of solution mixes soil removed from the surface with the solution and reduces cleaning effectiveness.
4. Prevent Flash Rust – When steel parts remain wet too long after cleaning, flash rust develops. This can occur even if the cleaning solution contains a rust inhibitor. To avoid flash rust, dry parts immediately after cleaning.
5. Synthetic Abrasive Pad – Use a synthetic abrasive pad on tough soils like welding smoke film.
6. How Clean is “Clean”? – Most steel has mill oil, processing lubricants and, in the case of hot rolled steel, heat scale. Oils, lubricants and coolants must be removed during cleaning to avoid paint problems. Most coatings will tolerate some heat scale on the surface, however, heavy deposits may compromise coating adhesion.
7. Cleaning Tests – After cleaning, lubricants, oils and coolants will show up as dark spots on the surface and also may show a sheen. Heat scale is less visible. Use the following tests to determine if the contaminants have been removed:
   -Spray water on questionable areas and watch for “water-break” or beading. If the water does not sheet over the surface, oil or other lubricants remain on the surface and must be removed before coating.
   -Wipe the underside of horizontal surfaces with a white cloth to check for heat scale. Usually, a light smudge on the cloth is not sufficient to cause a coating problem. If the cloth shows a heavy black smudge, affected areas should be recleaned and the process should be altered to insure that the underside of horizontal surfaces are clean.

For Technical Assistance Call:
1-800-888-1105

Hot Water Pressure Washing

Summary
This recommendation is for hot water pressure washing of metal parts and fabrications where the wash solution is sewered after use. The method described below is “one-step cleaning”. Parts are not rinsed with water following cleaning. Once all oils and other contaminants have been removed during washing, a water rinse is not required as Great Lakes Laboratories Prepaint Cleaners are non-filming and “paint compatible”

Equipment

• Hot water pressure washer – 1,500 to 3,000 psi
• Injector which allows high pressure injection
• 15° Wand Tip (routine cleaning)
• 0° Oscillating tip (rust, weld spatter, labels)
• Quick-Disconnect fitting for the wand tip

Product Selection

Method

1. Set temperature to 160°F at the wand tip.
2. Adjust injector so that 0.5 oz. of detergent is injected per gallon of water. Opening the injection valve 1/4 turn, is usually sufficient.
3. Adjust wand tip for horizontal fan spray
4. Begin at the top of the part and spray down using overlapping passes forcing soil down and off the part. Hold tip within 12″ of the surface and at a 45° angle downward to “chisel” off soil.
5. Once clean, air-dry or force dry the part.

Troubleshooting
Flash Rust on hot rolled steel is usually caused by parts remaining wet for too long after washing.
Insufficient cleaning may result from low solution temperature, low solution concentration and/or incomplete spray contact with surface.
Avoid white streaking on clean parts by reducing solution temperature, strength, and/or wash time.

Cleaning Tips

1. To eliminate hand-tooling, switch to the 0° oscillating tip to remove rust, weld spatter, loose paint and adhesive labels.
2. Tilt parts to minimize soil collection on horizontal undersides by reducing the surface area of the “drip point”. Tilting parts aids cleaning, draining and cuts drying time.
3. Hang parts on a swivel hook or place on a turntable. This allows the wash operator to remain in one position by rotating the part while washing. It also reduces wash time and overspray by keeping the spray directed into the wash bay.
4. To minimize operator fatigue, place the part so that the top is below eye level.
5. Bend wand 30° 4″ behind the tip to allow easier access to difficult-to-reach areas. Use a tube bender to avoid crimping the wand.
6. Avoid flash rust after washing by drying parts immediately. For castings, blasted steel and other highly rust-prone surfaces, All Purpose Prepaint Degreaser will prevent flash rust bloom when allowed to dry on the surface. Parts can be painted without rinsing off the rust inhibitor.
7. Descale heating unit coil on a regular schedule to maintain pressure and extend coil life. Clogged coils reduce pressure.

4 Key Variables In Water-Based Cleaning

1. Time – Length of time the solution contacts the surface.
2. Agitation – Impingement of the solution on the surface.
3. Concentration – Strength of the solution
4. Temperature – Each +18°F temperature increase doubles cleaning rate

Sewerability
Great Lakes Laboratories Prepaint Cleaner wash solutions may be sewerable depending upon the local industrial wastewater regulations.

Contact your local regulatory authority for the regulations on industrial wastewater sewerability.

For Technical Assistance Call:
1-800-888-1105

Industrial Roof Decking & Walls

Summary
This provides methods for industrial cleaning of roof decking, bar joists, trusses and walls. In many cases, water use is restricted because of water-damage risk to machinery, equipment, inventory and/or electrical service.

The products and methods described in this recommendation have been used successfully in auto plants, supermarket distribution centers, food processing plants, paper mills, paper converting facilities, airline hangers, diesel truck garages, fabrication/welding and grinding shops and warehousing operations.

Soil composition and surface conditions vary widely among different types of facilities and can also vary within a single facility. In most cases, surfaces are previously painted and require the removal of unwanted dirt, dust, oil film, exhaust residue or combinations of these soils.

Product Selection

Equipment

• Airless sprayer with 3′ gun extension
• Or, 2½ gal. plastic, tank-type garden sprayer
• Motorized lift, elevated platform or scaffolding
• Long-handled, soft-bristle, truck wash brush
• Rubber gloves
• Face shield or safety goggles with side shields
• Optional based on requirements
• Wet/dry vac or mop and bucket
• Compressed air or electric leaf blower

Procedure

• Select the Prepaint Cleaner most suitable for the requirements. Use trial samples for evaluation.
• Establish the solution concentration needed. See “Determining Concentration” section of this page.
• Mix Prepaint Cleaner with hot water, if available.
• Clean and dry one section at a time.
• Use a gun extension to increase reach.
• Use oil-free compressed air or an electric leaf blower to force dry the surface after cleaning.

>>Light to Medium Soil Conditions – In many cases, one-step cleaning of the surface is possible. The process involves applying sufficient solution to loosen the soil and flush it off the surface. An airless sprayer with an extension is recommended.

Roof Decking
-Spray in direction of channels or corrugation and work across bay forcing soil off the surface.
-Allow surface to dry then apply coating.

Walls
-Apply solution beginning at the bottom of the wall and work upward for the initial wetting of the wall. Once a vertical section has been prewet, spray from the top down, forcing soil down and off.
-Allow surface to dry then apply coating.

>>Heavy Soil Conditions

Roof Decking
-Prewet section with cleaning solution and allow 3-5 minutes contact time. Respray surface with solution in direction of channels and work across the bay forcing soil off the surface.

Walls
-Apply solution beginning at the bottom of the wall and work upward for the initial wetting of the wall. Allow 3-5 minute contact time, respray beginning at the top and working down, forcing soil down and off the wall.

Tips

• Use hot water if available as each +18ºF increase in solution temperature doubles cleaning rate.
• Use the minimum dilution of Prepaint Cleaner necessary to provide satisfactory results.

Determining Concentration

1. Mix 2 oz. of Prepaint Cleaner with 2 oz. water in a trigger spray bottle.
2. Apply to a test area representative of the surface to be cleaned. To test for one-step cleaning, continue to spray the solution onto the surface until the soil is flushed away. For heavy soil, spray the solution onto the surface, wait 3-5 minutes, respray with solution until soil is flushed away.
3. If the surface is clean, add 1 oz. of water to the solution and repeat step B, adding 1 oz. of water each time the test indicates that the surface is clean. When the solution becomes too weak to provide the desired result, use the previous, stronger dilution as the concentration for the job.

For Technical Assistance Call:
1-800-888-1105

Acid Etching Concrete Floors

Summary
Concrete floors require preparation before applying a paint, high-performance coating system, stain or a concrete sealer. The preparation usually involves cleaning the surface to remove oil and other unwanted contaminants then “profiling” the concrete by etching with acid or by mechanical abrasion.

If the concrete does not have heavy oil contamination, Great Lakes Laboratories Clean ‘n Etch will provide both the cleaning and the profiling in one operation.

For concrete with heavy concentrations of oil or other contaminants, clean the surface first with Great Lakes Laboratories All Purpose Prepaint Degreaser and then apply the Clean ‘n Etch for final cleaning and profiling of the surface.

New concrete may have been treated with a “cure & seal” to slow water loss during curing. Clean ‘n Etch will remove many of these compounds. Test by applying a drop of Clean ‘n Etch to the surface. If small bubbles appear, the Clean ‘n Etch is reacting with the cure & seal and will remove it. If no bubbles appear, Clean ‘n Etch will not remove it.

If the concrete has been steel-trowelled, the surface will be very smooth. This finishing technique works fine cement particles to the surface creating a very hard, dense finish. Steel-trowelled floors require a 1:1 mixture of Clean ‘n Etch with water and may require multiple applications to achieve the desired profile.

Equipment

• Plastic sprinkling can or 3 gal. plastic garden sprayer
• Push broom with natural or synthetic bristles
• Water for rinsing

Usage tips

• Work in 10’x10′ sections. Working in larger sections may prevent rinsing before the solution begins to dry resulting in white, powdery residue.
• If available, use a squeegee or wet-dry vac to remove the etching solution before rinsing.
• Do not apply the solution with a mop. Mopping smears the solution over the surface and does not supply enough solution uniformly for effective etching.

Optional Equipment Usage tips – Continued

• We do not recommend using a scrubbing machine as the brush or pad may be contaminated and may not provide sufficient agitation of the surface.
• Long-handled squeegee
• Wet-dry vacuum

Method

1. Dampen a 10’x10′ section of the floor. A little water on the surface helps activate the etching solution.
2. Apply the Clean ‘n Etch solution so that a uniform film covers the section to be treated.
3. Allow 5 minutes contact time.
4. Using the pushbroom scrub the solution into the floor working in one direction and then scrub across the surface at 90° to the first direction.
5. Allow the solution to remain on the surface for an additional 2 – 5 minutes.
6. If available, use a squeegee to remove the etching solution before rinsing. Otherwise, rinse using plenty of water. Scrub the surface while rinsing to insure complete removal of the etching solution.
7. Move to an adjacent area and repeat the process.

Troubleshooting

1. A white haze, white streaks or white, powdery dust on the surface after drying is caused by waiting too long before rinsing or by inadequate rinsing. The white powder is a combination of cement particles released from the surface and a precipitate byproduct of the etching reaction, insoluble calcium phosphate.

   Remove as much as possible by sweeping, scraping or vacuuming. A light dusting typically will not show through a clear coating and will not affect adhesion.

2. Look for areas on the treated surface that are darker or glossier than the rest of the treated surface. Water beading or breaking on these areas signals that the surface is not ready for coating application and should be treated again.
3. If water soaks into the treated surface without beading or breaking and the surface has the degree of profile specified by the coating manufacturer, the surface is ready for coating application.
4. Neutralizing the surface after etching is not required because Clean ‘n Etch is self-neutralizing. Once the bubbling stops, the remaining mildly acidic solution is easily removed by thorough rinsing.

For Technical Assistance Call:
1-800-888-1105

General Cleaning

For Technical Assistance Call:
1-800-888-1105