How to use polyurethane foam correctly: professional advice

Recommendation points

• Foam with a straw – the threat of expansion
• Assembly gun: price or quality
• Gun Foam – Professional Use for Beginners
• Initial installation of the gun
• Replacing the foam cylinder
• Sweeping the traces

From the article “Polyurethane foam: professional advice” you have already learned how to choose a quality product. The only thing left to do is to use it correctly. In this article, we will help you choose an assembly gun, we will reveal the methods of economical use and removal of foam residues from hands and clothes..

Despite the fact that assembly foam is in demand for arrangement and repair, do not forget that this is far from a universal insulating material. It all depends on the size of the gaps and voids that need to be filled:

1. Small cracks up to 1 cm are best eliminated with sealants or fillers. They are more flexible and will not have the side effect of secondary expansion..
2. It is recommended to fill holes more than 10 cm wide with static materials – bricks, wooden blocks or insulation (for example, foam), and only then additionally treat with polyurethane foam.
3. For insulating medium-sized cracks, it is optimal to use polyurethane foam – for household or professional.

Polyurethane foam sealant (polyurethane foam) has excellent adhesion to the vast majority of building materials, however, there are cases when it is useless: the foam will not stick to various types of polyethylene, Teflon, silicone, as well as to any greasy or dusty surfaces. These nuances must be considered in order to obtain effective insulation..

Foam with a straw – the threat of expansion

The main disadvantage of household foam with a straw is a significant secondary expansion. When hardening, it can increase several times, so it is extremely important to comply with all conditions of use.

The instructions for using household foam can be seen on the back of the cylinder, but we will consider it in more detail and step by step:

1. Cleaning and surface preparation. Before applying the foam, it is necessary to carefully check all cracks and holes for small debris and, if necessary, degrease the surface with acetone.
2. Moistening the surface. For curing, mounting foam requires contact with humid air, therefore, before using the spray can, the surfaces must be moistened – for this purpose, a conventional spray gun is quite suitable.
3. Preparing the foam cylinder. A little trick – before using the foam, you need to hold it for several hours in water with a temperature of about 20 ° C – after such a procedure it will lie down better. Before starting work, shake the can for a minute so that all components are evenly mixed, this will ensure maximum foam yield.
4. Attaching the tube or gun to the cylinder. The tube is simply screwed onto the valve, but with a pistol the situation is somewhat more complicated – we will consider the issue of its choice and use below.
5. Foam handling. According to the correct technology, the polyurethane foam is applied in small sections (about 10 cm) from bottom to top – this helps to avoid unnecessary spreading of the material. It is necessary to ensure that the gap is not filled by more than 50% – during hardening, the volume will increase greatly, which can lead to damage to the treated structure. It is extremely important not to touch uncured foam – any physical impact and violation of the structure worsens solidification and negatively affects volume and density.
6. It is necessary to ensure that the balloon is always in the “upside down” position – this will ensure the most complete consumption of foam.

Difficult moments:

Problem when using	How to solve
Foam opening more than 3 cm wide	Polyurethane foam must be applied in several steps, waiting for each of the layers to harden. Moisten the hardened base before reapplying the foam..
Through slots	In no case should such holes be filled with foam from both sides – this can lead to severe deformation of the structure. Foam is used on one side only, the back side is usually filled with silicone sealant.
Installation of door and window frames	To reduce the pressure on the structure, it is recommended to use dowels and additional spacers (they are removed after hardening). Otherwise, the foam, expanding, can thoroughly warp the frames of doors and windows..

A cylinder of household foam must be used completely, otherwise, during storage, the composition will harden and will be unusable. There are no such problems with professional foam, but there are some nuances..

Assembly gun: price or quality

A professional gun provides precise and dosed application of polyurethane foam, reusable cylinder use and accuracy during work. There are many modifications of such a tool, but the scheme of the device and the principle of operation are approximately the same:

1. Gun tip – as a rule, its diameter is several times smaller than the diameter of the tube itself. This feature allows you to multiply the pressure when the foam comes out, which, in turn, guarantees a good volume.
2. The trunk (tube) is the channel through which the foam comes out. Can be one-piece or collapsible (two-piece) for easy maintenance.
3. Adapter – an adapter for connecting to the neck of the foam cylinder. Teflon coated in quality models.
4. Adjustment unit – allows you to dose the foam output and its pressure.
5. Mounting nut – with its help the barrel is attached to the handle. This design allows the tube to be removed for cleaning or replacement..
6. Trigger – serves to adjust the supply of foam.
7. Handle – made of various types of plastic and metals. The most reliable and comfortable are aluminum handles..

The principle of operation of the assembly gun is based on simple mechanics: after attaching to the cylinder, the foam passes through the supply valve into the barrel, where it is until the trigger is pressed. Pulling the trigger opens the valve on the tip, releasing foam. The regulating mechanism allows you to control the volume of foam delivery.

Since there is nothing superfluous in the design of the pistol, choosing such a tool is quite simple. There are only a few factors to consider:

1. The quality of the materials from which the gun is made. It is best if it is made entirely of hard metals. There are high-quality plastic models, but this is very rare.
2. Collapsible design: monolithic pistols are cheaper, but the price of a collapsible tool will pay off many times when cleaning and replacing parts.
3. Working pressure in the gun. This characteristic cannot be checked in the store, but there is a little trick. When buying a gun, immediately purchase a can of cleaner (it contains acetone). At home, you need to screw the pistol onto a bottle of cleaning liquid, pull it inside by pressing the trigger, then remove it and leave it for a couple of days. If, after this time, acetone fires when the trigger is pulled, the pressure is normal. If not, you can return a low-quality product to the store, acetone does not leave any traces on the surface of the barrel.

Gun Foam – Professional Use for Beginners

With the right gun and related products (foam remover / cleaner and petroleum jelly) you can get to work.

Initial installation of the gun

To install the gun, unscrew the fastening screw all the way, grease the socket with technical vaseline and secure the cylinder. It is important to ensure that the adjusting unit is at a minimum foam consumption. Then the cylinder is turned over to the working position (upside down) and the composition supply is regulated – a couple of test presses are made to release excess air and check the pressure.

The rules for applying the foam remain the same: in small stripes from bottom to top. However, professional foam has practically no secondary expansion, which greatly simplifies the calculation of the required volume. The main thing is to make sure that the balloon is not in a horizontal position, both during use and during breaks..

Replacing the foam cylinder

Before putting a new cylinder or putting the gun in storage, it is necessary to thoroughly clean all surfaces from the remnants of old foam. For this purpose, a cleaner (wash) is used:

• to release pressure, pull the trigger of the pistol;
• fix the bottle with the cleaner to the gun;
• turning the cylinder over, press the trigger for 10 seconds;
• repeat several times until clear liquid comes out of the tube;
• lubricate the gun parts with petroleum jelly.

When storing the assembly gun, it is necessary to repeat the lubrication procedure about once every one and a half to two months.

When working with foam, it is important to take into account such points as its chemical composition and increased “stickiness” to different surfaces. Therefore, it is extremely important to use protective equipment – work suit and gloves..

Sweeping the traces

Polyurethane foam is one of the most difficult to remove materials: once it gets on fabric, leather or other surfaces, it is quite difficult to clean them. But it’s worth a try.

Surface	Fresh foam	Cured foam
Hand skin	Gently removed with a sponge, residues are removed with improvised means – scrub, acetone, solvent, gasoline, saturated saline solution	It can be removed only mechanically. Usually loses its properties and falls off after 2-3 days
the cloth	Collected with a stick, residues are removed with a cleaner. Important! Stains may occur when processing fabric!	If possible, large pieces are cut off, and the remains are treated with a special solvent for cured foam, white spirit or gasoline. Remove stains that appear with stain removers
PVC (frames, window sills)	Carefully removed, the surface is wiped with a special cleaner for PVC	Carefully cut, the surface is wiped with a special cleaner for PVC (usually marked – for installing windows)
Floor covering (linoleum, laminate, parquet)	Remove foam with a spatula, collect the rest with a sponge and cleaner. Stains may appear! They are removed from wooden surfaces by grinding, but varnished coatings cannot be cleaned – they will have to be replaced.	After cutting off the foam, the residues are carefully dissolved with a special cleaner or the drug “Dimexide” (sold in pharmacies). It is necessary to work with such substances with gloves – strong components can cause burns!

As you already know, polyurethane foam is not intended for sealing holes less than 1 cm in size – it is better to fill such gaps with silicone sealants.