August 7, 2026
Wheat paste is the adhesive technology behind every fly posting campaign. Here is how it works, how to mix it for different surfaces and conditions, and what professional crews know that DIY operations miss.
Fly posting paste is one of the least glamorous but most operationally critical elements of any street poster campaign. Get the paste right and the campaign holds through rain, wind, competing campaigns, and two weeks of foot traffic. Get it wrong and you are back on the route in 48 hours replacing pieces that peeled, bubbled, or fell off entirely before the campaign delivered any value.
Wheat paste — the traditional adhesive for fly posting — has been used for this purpose for more than two centuries. It is still used today, on professional campaigns by major labels, fashion brands, and film studios, because it works. The chemistry is simple, the materials are inexpensive, and the results when the paste is properly prepared and applied are reliable. But “properly prepared” is doing a lot of work in that sentence.
At American Guerrilla Marketing, paste preparation and application technique are part of how we train our crews. A poster that looks identical coming off the printer can produce very different field results depending on paste consistency, application sequence, surface preparation, and weather conditions. This guide breaks down everything our field teams know about fly posting paste: what it is, how to make it, how to adjust it for different conditions, and how to apply it to produce durable results across the range of surface types and weather conditions our campaigns encounter.
Wheat paste is a simple adhesive made from flour and water. The basic chemistry is straightforward: starch molecules in wheat flour, when heated in water, swell and bond together to form a gel with strong adhesive properties. When applied to a surface and allowed to dry, the gel loses its water content and the starch bonds form a physical connection between the paper poster and the surface substrate.
The adhesive strength of wheat paste comes from both the starch bonding and the mechanical bonding that occurs as the paste penetrates surface irregularities and dries into them. On a porous surface like brick or rough masonry, paste flows into the surface texture and creates a physical interlock as it dries — similar to how glue fills the micro-pores of a material and bonds to it mechanically. On smooth surfaces like painted wood or metal, the bond relies more purely on the adhesive properties of the dried starch.
Despite the availability of many more sophisticated adhesive technologies, wheat paste remains the standard for fly posting for several reasons:
The basic preparation method for wheat paste follows a consistent sequence. Deviating from this sequence — particularly on the order of mixing dry and liquid ingredients — produces paste with lumps or uneven consistency that affects application quality.
The flour-to-water ratio determines the viscosity of the finished paste. The right ratio depends on the surface type and weather conditions. Here are the working ranges our crews use:
| Ratio (Flour:Water) | Resulting Viscosity | Best Used For |
|---|---|---|
| 1:6 | Thin | Very smooth surfaces (painted wood, metal) in dry conditions |
| 1:4 | Standard | Most painted masonry, plywood hoardings, general use |
| 1:3 | Thick | Porous surfaces (raw brick, rough concrete), wet weather |
| 1:2 | Very thick | Highly porous surfaces, cold weather requiring extended working time |
These ratios are starting points. Actual paste consistency should be assessed by feel and application behavior before committing to a full campaign batch. Our crews test paste consistency on a small surface section before mixing the full quantity for a campaign run.
AGM Field Note: The paste consistency test we use in the field: apply a small amount to the target surface, press a piece of paper against it, and wait 30 seconds. Peel the paper back. If it releases cleanly with no resistance, the paste is too thin. If it tears the paper rather than releasing, the paste is appropriately bonded. Adjust the mix accordingly before running the full batch.
Standard wheat paste handles most situations well, but specific conditions call for modifications. Our crews use a consistent set of additives and adjustments that we have developed through field experience across different markets and climate conditions.
Adding a small amount of salt (approximately 1-2 tablespoons per gallon of paste) helps preserve the paste against mold growth when it is stored between use. Wheat paste is an organic material that begins to break down if stored at room temperature for more than a day or two. For campaigns with multiple posting days spread across a week, preserving the paste batch between sessions saves remixing time and ensures paste consistency is maintained across the full campaign run.
Refrigerating stored paste extends its viability significantly — a refrigerated, salt-preserved paste batch can hold for up to a week without significant quality degradation. We seal paste containers tightly before refrigeration to prevent surface drying and skin formation on the top of the batch.
For difficult surface types — very smooth non-porous surfaces, surfaces with residual moisture, or surfaces in markets with particularly wet climates — adding a small quantity of PVA (polyvinyl acetate) wood glue or similar commercial adhesive compound to the wheat paste improves bond strength and moisture resistance. The typical addition ratio is 10-20% commercial adhesive to 80-90% wheat paste by volume.
The tradeoff is that PVA addition reduces removability: the resulting paste is harder to remove from surfaces and may leave adhesive residue that requires more aggressive cleaning. For campaigns on surfaces where the property owner requires clean removal at the end of the campaign period, we either avoid PVA addition or use it only on the surface coat, not the top seal.
In cold weather (below 45 degrees Fahrenheit), paste thickens faster as it cools and becomes harder to work with. We mix cold-weather paste with slightly warmer water to extend the working time before it thickens at ambient temperature. In hot weather (above 85 degrees Fahrenheit), paste dries on the surface brush faster, reducing working time for poster placement. Hot-weather paste is mixed slightly thinner to account for faster evaporation, and we work in smaller application areas to ensure the paste is still wet when the poster is positioned.
The relationship between paste and surface is the most important variable in fly posting durability. Different surface types have different absorption characteristics, different texture profiles, and different chemical properties that affect how paste bonds to them and how long that bond holds.
Plywood is among the best fly posting surfaces for paste adhesion. The surface texture provides mechanical interlock points, and the wood’s mild porosity draws paste into the surface and creates a strong physical bond. Standard viscosity paste works well on clean plywood. The primary challenge with wooden hoardings is surface cleanliness: paint, grease, or previous campaign residue on the surface can reduce adhesion. Our crews assess hoarding cleanliness before posting and clean surfaces with a dry brush when necessary.
Painted plywood accepts paste slightly differently than raw plywood. If the paint layer is in good condition, paste bonds reliably to it. If the paint is peeling or loose, the poster will detach with the paint layer rather than holding to the wood. We avoid surfaces with active paint failure.
Brick is the most common urban wall surface for fly posting and also one of the more demanding from a paste perspective. The porous, irregular texture of brick absorbs paste rapidly, which means standard-viscosity paste can be drawn into the surface too quickly before the poster is positioned, leaving insufficient paste at the paper-to-surface interface for a reliable bond. We mix paste to higher viscosity for brick surfaces, and we apply a heavier first coat than we would on smoother surfaces to ensure sufficient paste remains at the interface after absorption.
Mortar joints in brick walls are particularly absorbent. If a large portion of the posting area falls on mortar rather than brick face, we apply additional paste specifically to those sections before positioning the poster. Failing to account for mortar absorption is one of the most common causes of edge lifting on brick installations.
Painted concrete, stucco, or masonry surfaces are generally good fly posting substrates if the paint layer is intact and in reasonable condition. The paint provides a relatively smooth, moderately porous surface that bonds well with standard paste. If the paint layer is glossy or very smooth, adhesion is reduced and a thicker paste or PVA addition may be needed.
Age and weathering of the paint surface significantly affects adhesion quality. Fresh paint creates a slightly different adhesion profile than paint that has weathered for several years. Our crews assess each surface individually rather than applying a single approach to all painted masonry.
Metal surfaces are among the most challenging for wheat paste because of their non-porous nature. Standard wheat paste relies partly on mechanical bonding through surface porosity; metal provides no porosity, so the bond is limited to the chemical adhesion of dried starch to the metal surface, which is significantly weaker than bonds to porous substrates.
For metal surfaces, we use paste with PVA addition, apply a heavier surface coat, and ensure the top paste seal coat is complete and edge-to-edge. Even with these modifications, posters on metal surfaces typically have shorter hold times than those on wood or masonry, and we factor this into maintenance cycle planning for campaigns that include significant metal surface placements.
AGM Field Note: Scaffolding panels — the opaque boarding panels used on construction scaffolding — are often treated with weather-resistant coatings that affect paste adhesion differently from untreated metal. We test a small area before committing to a full installation on scaffolding panels we have not previously posted on, and we adjust paste formulation based on the test results.
The paste formulation is only half the picture. How paste is applied determines the installation quality as much as what is in it. The application sequence we use is consistent and specific, and deviations from it reliably produce quality problems.
Before applying any paste, the crew member checks the surface for:
Surfaces that fail this check are either cleaned (if the issue is dirt or grease) or flagged for substitution with an alternative surface on the route. Posting on a bad surface produces a bad result regardless of paste quality.
Standard fly posting application uses two paste coats: one applied to the surface before the poster, one applied over the poster after placement. Each coat has a specific purpose.
The first coat (applied to the surface) creates the adhesive interface that bonds the poster to the wall. It should cover the full area where the poster will go, plus a margin of two to three inches on all sides. The margin paste is important: it provides the adhesive bed for the poster edges, which are the most vulnerable points for delamination.
The second coat (applied over the placed poster) serves three functions: it seals the poster edges against the surface, creates a moisture barrier over the poster face, and provides additional adhesion at any points where the first coat was insufficient. The second coat should be applied from the center of the poster outward to avoid trapping air bubbles, and it should be complete from edge to edge with no gaps.
Air bubbles under a posted piece are both a visual quality issue and a structural one. A bubble is a point where the poster is not in contact with the surface, which means it is not bonded there and is vulnerable to catching wind and delaminating. All bubbles visible after initial poster placement should be smoothed out toward the nearest edge before the top paste coat is applied.
The smoothing tool varies by crew preference and what is available. A broad paste brush, a plastic squeegee-type tool, or simply a flat piece of rigid plastic all work. The important thing is using firm, consistent pressure from the bubble toward the nearest open edge, never from the edge inward (which can trap air rather than releasing it).
Weather is the factor most likely to affect fly posting quality that is outside the crew’s control. Understanding how different weather conditions affect paste performance allows for adjustments that minimize weather-related campaign problems.
| Weather Condition | Effect on Paste | Adjustment |
|---|---|---|
| Cold (below 45F) | Paste thickens rapidly; reduced working time; slower curing | Mix with warmer water; work in smaller sections; avoid freezing temperatures |
| Hot and dry (above 85F) | Paste dries quickly on brush and surface; reduced working time | Mix slightly thinner; apply to smaller sections at a time; work faster |
| Rain during posting | Dilutes paste, weakens wet bond; paper soaks and tears | Reschedule to dry window; prioritize sheltered surfaces; use PVA addition |
| Rain after posting | Can weaken uncured paste bonds in first 2-4 hours | Post before forecast dry window; allow curing time before rain exposure |
| High humidity | Slows paste curing; extended vulnerability window | Use thicker paste; avoid if humidity extreme; ensure top coat is complete |
Rain is the most significant weather variable for fly posting campaigns. Our approach is to work posting schedules around forecast weather windows whenever possible. A dry 48-hour window after posting allows paste to cure sufficiently to withstand subsequent rain exposure. If the forecast shows rain within six to eight hours of a planned posting session, we typically reschedule or concentrate on sheltered surfaces for that session.
For markets with consistently wet weather — the Pacific Northwest, for example, or London in winter — we add PVA to all paste formulations as standard and accept that maintenance cycles will need to be more frequent than in drier markets. Campaign planning for these markets accounts for this from the start.
Estimating paste volume for a campaign is practical knowledge that prevents the crew arriving at the wall with insufficient paste for the full route. Under-preparation means either returning to mix more (time cost) or leaving placements incomplete (quality cost).
As a working guideline, we estimate approximately 1 gallon of paste per 20 to 30 standard single-sheet placements (17×22 inches), accounting for both the surface coat and the top seal coat. This figure varies based on surface porosity — highly porous surfaces consume more paste per placement — and poster size. For a 50-piece single-sheet campaign, we typically mix 2 to 3 gallons, building in a buffer for reposting at any surfaces that need a second attempt and for paste that is lost to brush cleaning and container residue.
Large-format multi-panel installations consume significantly more paste per piece. A 4-sheet assembly (approximately 40×60 inches) uses four to five times the paste volume of a single-sheet placement. For multi-panel campaigns, paste volume needs to be estimated specifically based on the panel dimensions and the number of placements.
Paste is mixed in advance of posting sessions. For large campaign days, we mix paste at a central location and transport it in sealed 5-gallon buckets. For smaller routes, we sometimes mix paste in the field using portable equipment when mixing space is available near the posting area.
Paste should be used within 24 to 48 hours of mixing for best performance, or refrigerated and used within a week. We do not use paste that has developed an off smell or visible mold growth — these are signs of bacterial activity that degrades the starch bonds and reduces adhesive performance.
Wheat paste is the standard, but it is not the only adhesive option. Understanding the alternatives and when they are appropriate is part of professional campaign planning.
Methyl cellulose (also known as methylcellulose or MC) is a synthetic cellulose-based adhesive that is used by some poster conservators and papier-mache artists for similar purposes to wheat paste. It has some advantages over wheat paste for fly posting: it does not support mold growth as readily, it has more consistent viscosity from batch to batch, and it tends to remain more flexible when dry, which can reduce poster cracking in very cold weather.
The main disadvantage of methyl cellulose for fly posting is cost: it is significantly more expensive than wheat flour per unit of paste produced. For large-scale commercial campaigns where cost matters, wheat paste remains the primary choice. Methyl cellulose is sometimes used for smaller-scale or premium campaigns where budget is less constrained.
Heavy-duty wallpaper adhesive, available at hardware and home improvement stores, is another option for fly posting on specific surface types. It typically provides stronger initial tack than wheat paste and better moisture resistance, making it appropriate for surfaces where wheat paste performs poorly. Cost is higher than wheat paste but lower than pure commercial adhesive compounds.
The tradeoff is that commercial wallpaper adhesive can be harder to work with at scale — it tends to be more viscous than wheat paste, which makes it harder to apply evenly over large areas with a broad brush. We use it selectively for specific surfaces rather than as a general replacement for wheat paste.
Professional fly posting campaigns include paste preparation, crew labor, route execution, and documentation as part of the installation service. Our pricing for managed US route campaigns:
| Campaign Scale | Placement Volume | Scope | Installation Price Range |
|---|---|---|---|
| Small | 25-50 placements | Single city | Contact for quote |
| Mid-scale | 75-200 placements | Single city | Contact for quote |
| Large | 200-500 placements | Single or multi-city | Project-specific (contact us) |
Multi-city campaigns at large scale require four to six weeks of lead time for route coordination and crew scheduling. Print production is quoted separately based on format size and quantity. Call (646) 776-2770 or email [email protected] for a complete campaign estimate.
Traditional fly posting uses wheat paste, made from flour and water cooked together until it forms a smooth, consistent gel. Modern campaigns sometimes supplement with commercial adhesive compounds for specific surface types or weather conditions.
Mix flour into cold water to prevent lumping, then heat while stirring until the mixture thickens into a smooth paste. A standard starting ratio is approximately 1 part flour to 4 parts water, adjusted based on surface type and weather conditions.
A poster applied with proper wheat paste technique can hold for two to four weeks or longer depending on weather conditions, surface type, and whether the surface is sheltered. Exposed surfaces in heavy rain require more frequent maintenance or reinforced adhesive formulations.
Wheat paste is natural, easy to mix, and bonds well to most outdoor surfaces. It breaks down more quickly in persistent wet conditions. Commercial adhesive compounds (PVA-based or similar) provide stronger initial bonds and better moisture resistance, making them suitable for difficult surfaces or wet climates.
Wheat paste is water-soluble and does not chemically damage most outdoor wall surfaces. It bonds to the surface layer and can typically be removed by soaking with water. Professional campaigns use paste appropriate to the specific surface to minimize any surface impact.
Porous surfaces like raw brick and concrete absorb paste quickly, requiring higher-viscosity formulations or multiple paste coats. Smooth surfaces like painted masonry or plywood accept standard paste well. Very smooth non-porous surfaces may require a commercial adhesive compound to bond reliably.
Cold weather thickens paste and slows curing. Hot, dry weather causes paste to dry too quickly on the surface. Rain after application can weaken uncured bonds. Our crews adjust mixing temperature and paste viscosity based on weather conditions at the time of posting.
Yes. Adding a small quantity of PVA or similar commercial adhesive compound (10-20% of the total volume) to wheat paste improves bond strength on difficult surfaces. Adding salt helps prevent mold growth in stored paste. Adjusting the flour-to-water ratio increases or decreases viscosity for different surface types.
A rough estimate is approximately 1 gallon of paste per 20-30 standard single-sheet placements, accounting for both the surface coat and the top-sealing coat. Large-format multi-panel placements use significantly more paste per piece.
Poster campaigns are priced by package and market. Standard poster campaigns (24×36) start at $4,500 for 100 posters (two-week run) and $5,500 for 200 posters. Large format (48×72) campaigns start at $10,500 for 100 posters and $13,500 for 200. An optional two-week maintenance extension is $3,500. Contact AGM at (646) 776-2770 for a custom quote based on your market and objectives.
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American Guerrilla Marketing — Los Angeles
Street-level campaigns in Los Angeles and nationwide. Wheatpasting, LED trucks, street teams, and more.
(646) 776-2770
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